No, it wouldn't. A properly balanced creature can take their action along with the caster and wouldn't feel completely artificial like it does now. If the DM adds a couple minions to most encounters it won't break things, likewise if a player could bring in a couple vanilla minions it isn't going to far and away outstrip other powers.
Even if you had "economy of action" and had to give up your action for your summon to act, a 3.5E 17th level wizard would gladly give their action for a gated 34th level Solar to take theirs! "Economy of action" is utter drivel. Balanced companions and summons are the answer.
A summon balanced the way you suggest would do in the area of 1d4+Int damage at level 1, maybe 1d6+Int.