I've never owned a plane that wasn't a trainer. (beginner plane)

I've always heeded the advice about a plane's intended audience in regards to skill level and I've never questioned that an Extra 300 or a Bipe is not for beginners.

However...

I started thinking tonight. (dangerous as that may be)

What exactly makes any plane so difficult to fly?

Example:

I take a the Sukhoi out to the runway. Give it some throttle and pull some elevator. Get some altitude. OK, maybe it is going to fly and land faster, but would I be able to fly it around in a circle at 1/2 throttle or will it fall out of the sky?

Face it, Trainers can be difficult for beginners.

Of course there is the obvious like speed, dihedral, flat bottom vs. symmetrical wing, and such but are the more "advanced" planes that significantly different when it comes to basic flight?

If so, how?

Elaborate

Why can't I fly that Giant Bipe??


Thanks