Why do you have to be a MUCH BETTER player than your opponent to prevent those draws?
You can't prove anything from the fact that ughaibu doesn't let many players draw. (And some players wouldn't even when they had the chance.)
The point is, that two equally strong players should have around the same 'chance' to win. Now, white is already favoured by the rules (60%!!), which is -to say the least- a reason to abolish perpetual raichi.

Besides,
when you place the burden on black to prevent perpetual raichi, his/her range of moves is seriously limited.
It could even mean that the black player has no choice at all in the opening. That would make the game less interesting: less chance to develop your own style etc. The use of different approaches to white threaths is what makes the black part fun.

We are now talking about arguments against perpetual raichi, but what are the positive reasons perpetual raichi should be allowed?