Because trike gear on a biplane is just..... just..... well, just.....

WRONG



The only one in the full sized world that I know of is a Waco Cabin Special or something with a lot of odd letters. And it just looks odd.

Conventional isn't all that hard. I've flown both and conventional is actually easier in some cases. The cross wind takeoffs are just a bit harder than trike. And there's a few tricks to setting the toe in and stuff that you can do later if the ground handling is a problem.