These things would be good but they wouldn't change the general incentive. There are still plenty of instances that are properly "funded" but still go under, lemm.ee being the most recent example. The problem is that these donation-funded instances are bound to hit a ceiling even when they hit their raising targets.
Mastodon instances that have good transparent reporting of their status (hachyderm, fosstodon, mastodon.social) are all receiving enough donations to support the hardware, but no one accounts for the labor of the admins and moderators and these are the real operational costs for the instances - and no one wants to pay for those.