1.According to the Star Wars Databank, it can hold up to 6 speeder bikes
so why it has no docking bay?
2.If there is a disparity between technical data of Combine entities and their real data , can the Combine ones be changed?So can it be suggested(if it has prove from the Star Wars databank and so on) and have a chance to be accepeted?
This isn't the suggestions forum, so to answer your question, it was likely either an oversight or it was intentionally omitted to achieve balance.
As a sidenote, it is the hangar bay that holds vehicles here, and the docking bay holds ships, so what you would be suggesting (again, this being the wrong forum for suggestions) is the addition of a hangar bay.