The flash has so little survivability you can die from hitting a tree. Once you get 30+ dudes all flashing towards a base, you're nigh guaranteeing that they're not going to get there at the same time, and some may not make it at all. (Though I'd LOVE to see that and could see, with practice, a team of people using such tactics for quick-strike infantry.)
Of further import is the design of the bases. A Sunderer is capable of ramming its way INTO the base and dropping off its payload under cover, bursting through the front lines.
That being said, Galaxys are the best and Galaxy pilots are the best people.
and PDog, who says my Galaxy can't sneak?