Savoy ... to answer your question simply: more teams = more playoff teams.
I'm still a rookie here (at least comparatively in terms of experience) so I confess, I've never participated in anything but a 24-team league. But the reason I've steered away from the 16 (didn't know there was a 30) is the fact there are only four total playoff teams, compared to 8 in a 24.
In a 12 ... obviously that numbers shrinks even more to two.
I share in your criticisms of the 24-team schedule, especially in relation to the number of games against division foes. (I don't really care about the interleague complaint.) However, if there's one thing I've learned in the WhatIF world, it's the fact there's some real sharks swimming in these waters who out of 100 seasons, would best me (and the vast majority of us) 80-90 times.
I know the names and when i see myself in a division with them, i take solace knowing no matter what, I can still get in to the playoffs as a wild card team.
My goal each season is to make the playoffs and see what happens. And as I see it, my chances of doing that are a lot better (twice as good in fact at 1 in 3 instead of 1 in 6) in a 24-team league compared to a 12.
It's a shame as I really like random leagues and am in a random box score league now with an $87M cap. It's a lot of fun to build a team like that, but I would be interested in comparing the building process with a $100M budget.