I like playing "mages" champion. I play mages in mid, I play mages in support, heck if I can I play mages in jungle (Wait, I do that sometimes, too. 
)
But I play different ones in different role. For zyra I play her as a support. But for mid I do not. So why is that? Because there are mages at the mid that currently function like a better version of "mid zyra".
currently is a mage that is.
- Have no blink/dash ability for kiting. Basically not very mobile.
- Have poke in lane that also function as wave clear.
- Have some CC for kiting, teamfighting, and for creating picks.
- Provide zone control through damage, and the aforementioned cc.
- Mostly associated to be a burst oriented mage.
She can do this as a support or a midlaner. But you know who else does that as a midlaner? Quite a decent amount of them actually. To name a few 
.
Buffing scaling and lowering her overall base damage essentially with move her toward more that subset of midlaners. She may have a different kit and feels different compare to the other champions, but functionally she would provide a similar ultility for the team. The end result is you get another midlaner for that subset of mid lane mages that is already quite abundent but lost one of the very few mages that function quite well as a mage support. (For that mage support subset, there is basically 
>
and maybe ; I believe Zyra is probably the best in the mage support subset of champions. )
So for me at least I rather to have stay as she is. Since I already have more than enough mages to choose from in the mid lane which is traditional where mages goes, and have a much more limited choices in the support role.
