Kinda defeats the purpose of a portable system.
I agree
Not really.
Unless you are an EXTREME HANDHELD GAMER (running around your house/neighborhood/Wendy's), you tend to be pretty damn stationary when playing.
And, as 420GOAT stated, he doesn't always want to wear headphones. So we are left with the valiant but all-too-hollow-sounding built in TE/GT speaker.
I WANT MY WALL OF SOUND.
Especially when playing TG-16. And PCE.
Remarkably, it takes mere moments to plug my TE/GT into a home stereo/boombox/car sound system/etc.
ALSO: 420GOAT and I are often unable to use the television/room with television because they are occupied (kids, spouse, kids' friends, spouse's friends, etc.) so... that sucks.
Additionally, for me (I can't speak for 420GOAT), I can't leave my two 13-month-olds alone for more than a minute without worrying about them.
So, the TE is a convenient, flexible, non-intrusive way to play some TG-16. Hell, I use an AC adapter 80% of the time.
BUT WHY SHOULD I SACRIFICE WALL OF SOUND?
I want my wall of sound.
Then again, I am not an XTREME HANDHELD GAMER who sprints about, performing pirouettes and demi-pliés whilst playing Dragon Spirit.
Although, I must admit that it would be satisfying to grand-plié upon 1CC-ing Dragon Spirit.
Hmmmmm.