Question for all Yiquan practictioners:
Why not just practice Yiquan rather than practice more of the internal arts as Yiquan is formless and can adopt the energies etc from the other arts?

Cuz' some of us like those other styles!
Why not just buy a gun!

How can you "adopt the energies etc from other arts" unless you study/train those arts?

No art is "formless." Yiquan contains a fair number of forms called "shi li" (power testing).

It's important not to mistake a particular variation of an art as being somehow superior to any other variation because said variant has more or less "forms," or special techniques etc.

What is fundamentally important is to look for the underlying principles, then you'll see through the artifice of "styles."