This is a neat thought experiment. I expect most teams would still select the top spot available and there are often booing accusations following a decline.
Raising the minimum number of teams would also decrease the serpentine's bite but I suspect most venues are near capacity already.
# of teams | minimum elimination robot percentile
30 | 0.2
36 | 0.33
42 | 0.43
48 | 0.5
Allowing the top alliances to select their opponent from those below them each round would help the stronger alliances to advance.