1. Certainly agree the linkage between long-resting and plot-related party conversations is sub-optimal. This is particularly true as the (seemingly) very non-linear story leads to a difficult tangle of subsequent conversation triggers, some of which can invalidate earlier conversation triggers before they have a chance to activate.
I understand the production reasons for wanting an invariant camp backdrop when enacting these hi-res cut-scene conversations. As you say, it's usually better not to force players into any particular behaviour, so I would prefer they find a way to allow conversations to trigger "in the field" where possible, rather than contrived penalties, which tend not to be popular.
Of course, if Larian choose to add the passage of time to their game, the reasoning changes; but I don't think that is likely.
2. Quantity reduced, or heal values lowered or weight increased could all achieve the nudge towards long resting, but at the expense of reducing player choice. Can't say I care much one way or the other, but as with other player choice limitations, this can often prove unpopular. And, of course, not needed if you can trigger conversations in the field.
3. Yeah, why not ( apart from the fact it will induce apoplexy in some people ). I really don't care much about ability balance in games. As long as I can see upfront what I am going to be choosing between, I can make my choices from whatever the game maker offers. As with most design decisions, whether changes lke the ones you propose are necessary or desirable is probably a matter of personal opinion. Most BG3 players probably wouldn't care, and those that do would turn to mods.
As for BG3 long resting, I think Larian's current decision to allow long rest at will and with no penalty is fine. There isn't ( tadpole notwithstanding ) any obvious time pressure present in Act 1, which is more useful to gain experience,build up knowledge of the situation, and establish relationships with other actors in the story.
Later, the story may have time pressures or penalties that will cause players to think twice about a long rest. Or not. There shouldn't be contrived reasons that the story doesn't need.