Wait... you mean you have to choose what nano to cast? You can't cast 2 at once? Welcome to the world of caster professions; get over it. Sometimes you have to make choices and sometimes you die (*gasp*).
Flaming aside, this is a terrible reason to make agents more powerful than they already are... agents are great gankers and that's what theyre intended to do. If any agents have problems PvPing, it is very likely the player and not the profession. See marineagents new pvp video if you need tips