Well, as the Arverni/Aedui, the only missile troops you have access to are sotaroas, iaosatae, toxotai or sphendonetai. In other words, there's not much glory there to be found in the first place, and what you have can easily be taken care of by most enemies' missile units. That the best of them, the sphendonetai, count against your allied/merc slots, for which you have much superior contenders, doesn't exactly make the choices better. So by throwing missiles away alltogether, you are not losing much to begin with.

Now, if you did this and thought that you still could just sit around and play with your prick while the enemy bombards you with missiles and perfecting his own positions, then you truly deserve to lose. No, this choice is of course dependent on you playing a very aggressive style; it's all about taking and making the initiative yours. Naturally, if you succeed, he will not be able to fight the way he wants, but will be forced to simply react to your moves instead.