For a game with Diablo-like loot system, that is, with tons of various items to sift through, having the option to sell junk in bulk is a necessity.
The option was first introduced in Borderlands 2, but it was implemented poorly back then (even more so on PC): first – one had to aim to a corner of each item’s icon to mark/unmark the item as favorite or junk (console gamers could simply press L3 to toggle the marking), second – “sell junk” shortcut only applied to marked items, which, given the first problem and the sheer number of items in loot, required way too much menial labor.
The option was fully implemented in Borderlands TPS, where “sell junk” was changed to “sell all not equipped/locked” – no more manual work, and no need to mark tons of trash by hand.
Now, similar markings are introduced in Borderlands 1 GOTY Enhanced. Markings are still not linked to keyboard, but that’s only part of the problem, as usability is even worse than it was in BDL-2 at release: “sell junk” option is moved from main trading tab to “Sell” tab, which has to be activated with a click, because tab switching on PC is not linked in any Borderlands game up to TPS. So, it boils down to manual marking plus manual switching and then using the “automatic” selling command, or only manual switching and selling items by hand just like before.
There was an existing and convenient solution made within the same series, but you chose to take an old underdeveloped solution and make it even less useful. For the love of the Vault, why?