I suggested something like this back when I joined osu! and the priority system was still newly implemented. There really needs to be more variance in how much a mod post is worth instead of fixed values and abuse of the 2kd bonus.
As has been brought up in various places, there also needs to be more moderation on what constitutes giving kudosu and what doesn't. There's too much gray area and inconsistency. There's mappers giving kd for non-mod posts (dealt with once BATs check the threads); there's mappers giving kd for non-helpful/unsubstantial posts (e.g., a few lines of combo mods, nazi mods, "your inherited section is off by 3ms", "+2 your offset", etc); and there's BATs that still incorrectly give/receive kudos even though they're well-aware of what should and shouldn't receive kd (e.g., guest difficulties aren't supposed to receive kd, yet a few BATs still hand out kudosu and willingly accept it).
2kd for a single mod post should be the upper limit (i.e., 3 is too high), and I agree that the mapper should be able to select between 1 and 2 kd. Perhaps the 2kd bonus (for no posts in a thread for a week) could be either changed to taking 2-3 weeks without posts/updates or just removed entirely, but this is a slightly separate issue.
tl;dr - We need to regulate kd more (with strict guidelines/rules and actually taking action when we see abuse) and allow true helpful/extensive mod posts to receive the credit they deserve.
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