394136
I agree with you!

I like ponies with socks; they're freaking adorable! I just also like justifying the reason in-universe, it helps to make everything more cohesive. As for the art, I interpret it as Twilight working on her concentration like in Magic Duel. I like the proportions on the Dash one. She has a realistic amount of body fat and I think she looks very graceful.

We don't seem to have any real disagreements over this(which is nice).

394131 The magic of friendship is constantly portreyed as the strongest of Magic, but it only work in a group where one can chanel the combined efforts. We have numerous occasions to the effect.
They have several good reasons, not to like dressing up. For one, it is a hindrence to flight, which is esential to Pegasi culture like in Cloudsdale.
The reminder of the Windigo incident should be a sore point to them, they were not exactly helpful here, untill in the very end.

Cloudsdale is the Pride of pegasi. If it was a penance, the weather and cold up there could be a case. Yet, they have constant sunshine as well as a payment. They may very well have a different fur with more under fur to deal with the cold winds up there.
Earth Pinkies and Unicorns seems rather comfortable with lothes to their varying degrees. Clothes are used to make you either special, or protect you against the wear and tear of a hard work. Feels reasonable enough.

Wings, that would apply to the Alicorns as few as they are as well. Current rate is a total of Four known Alicorns.
Temporary, or better referred to a Winged Unicorns like Rarity. If the wings actually are a part of the Pony or not would depend on a case by case.

Socks and boots seems more like regular ornamental or weather protection, if and when needed.
Stockings, or tights are commonly considered lingerie. Just that it would be troublesome and problematic to make tights for a Pony.

Since we are here, I feel it is safe to expect you to enjoy them wearing these socks, why else being here?
Since no clear statement to the effect is up on the front, one may question if you prefer them as Lingerie, or more munsdane ornamental or work related?

I sure enjoyed the boots Rarity was wearing at the time. I enjoyed the once Pinkie Pie wore when she wa chasing Cake Twins too.
Socks has been with us from early MLP, or before the FiM. These are commonly cute, not so much of lingerie.
The lingerie and stockings should be plenty of fun, but we never see bedside play in MLP since it is said to be targeting little girls,
something we don't need to worry about when writing stories and drawing images, in which ever style we may choose.

Interesting interpretation of what looks like a Future Twilight Sparkle here. Just how far in the future is this expected to be?
Not sure what to sy about the interpretation fo Dashie.
A sweet moment by the lake side with Twilight and Dash. A shipping opportunity, right there.
Another future Twilight Sparkle.

394068
Agreed.
I think the ponies -specifically pegasi- have little want for clothing that doesn't serve a specific purpose; fireproof and winter boots are for extreme temperature differences, something they either cannot physically stand or intensely dislike. I can see them have a cultural dislike of clothing due to the Wendigo Winter. It was something that was required to survive the harsh climate and could be associated as a constant reminder of their continued predicament. It was something they thought couldn't be change with any amount of pony magic. Until the Fire of Friendship, anyway.

The cultural heart of the pegasi -Cloudsdale- is fucking cold and, while they would eventually acclimatized (or potentially already have; depending on how long you see the WW lasting) to their new environs, maybe they see it as penance for their failures to stop the weather change. This would give them thicker, dual layered, fur -I wonder how cuddly- amongst other advantages like a firm layer of fat for the climate. You can see the opposite with the earth ponies and unicorns, as you said.

Pegasus have another reason for not wearing clothes; their wings, they don't have need for them.
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I really want to cuddle with them!

394056 Sometimes, they give the feeling clothes are mainly to exclusively worn by upperclass, Unicorns.
The Lower class Earth Type merely use what is passing for clothes as protection at work, even if they probably wear them all day.
Pegasi nearly never have use for them, aside from the select few like the Wonderbolts.

Then comes the aspect of Winter and Lingerie. If you freeze, you wear clothes.
To bed, you may choose to wear the Lingery as a spice for your special some Pony.

For Ponies, I imagine the socs reaching just above th heal, which in this case is where your knee would have been. Only pointing bckwards for the Pony.
I had the impression from the art, that it commonly is Stockings that were considered Lingerie, which reaches half way up the leg from the point where the socks ended.

Hmm, Dash in Sleepwear, I would have to see this in Canon. Wearas some other Ponies does wear it, most likely would be Rarity, as a Unicorn?

When it is cold, I recall them wearing boots, most all the Ponies wore them. As exiting as some of us may have seen them, I doubt they saw them in this light.
Wearing them in bed would make them into Lingerie, right?

Dash rarely wear anything. Granted, she wore the gawn at the Gala, but otherwise, just the boots and the suit for the contest?

392880
Either or, I think it depends on the pony. Rainbow Dash might only wear them on her hindquarters or just regular sleepwear like so:
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As to your second, I think it depends on the context. If socks are sleepwear; do you see them as lingerie? They serve a practical purpose if you put the story during the winter schedule. Maybe Rainbow uses a combination -hindquarter socks under sleepwear- in a sleepover.
Now I can't get that out of my head...

Would you prefer the Pony with socks on her hind quarters, or all fours?
Does any other clothes add to the feeling or are they distractions or merely in the way?

Since I am new here, I will have to ask around. Besides, now I am writing a new story where a Pony will be wearing socks, as per the title of our Group.

Incidentally, I chose Pinkie Pie. Hope you will enjoy the story, once I can publish the first chapter.