Disagreed. Games like Fortnite and League of Legends went down this road and ended up at even more unfathomable $500 microtransactions. The only issue with skin trading is that people will take it more seriously than it is, which is a problem with all cosmetic systems.

There are huge gambling cultures around skins. All kinds of theft and scamming. There is no "only issue". There are tons of issues

Nah. Digital items should be transferable, similar to physical gacha like Pokemon cards.

That doesn't mean they should be reliable speculation vehicles. AFAIK Valve hasn't interfered with the gifting of digital items, only sales.