I can't believe I'm saying this, but I actually think that your interpretation nerfs gate too much, Shard.
In general, the calling spells (planar ally, etc.) are far more powerful than the SM spells. In fact, the SM spells by and large are rather on the weak side for their level at ANY level. The designers clearly felt that calling spells somehow had a counterbalancing weakness that made them competitive with summon spells (if there is one, I don't see it).
IMC, I use the following rules for gate: 1) the spell has a 5000 xp cost; and 2) it confers no control whatsoever over the creature summoned.
If you all think this is too harsh, think of it this way: As it stands, gate is not only the best summoning spell (a 20th-level caster can summon an infernal, a CR 31 creature, while still maintaining control of the creature), but it allows instantaneous travel to any plane desired (thus being better in many ways than astral projection, another 9th-level spell), it allows foolproof assassination (go to another plane and gate in your enemy, command him to fight for you against an invincible foe or just stand still for a round or two), and it allows an unbeatable defense (conjure a gate with the open side facing away from you, allowing you to launch attacks normally while all attacks launched in your direction end up in another plane). All of these things make gate well worth the 5000 xp cost and loss of creature control in my games, and I imagine they will in yours as well.
BTW, the potential roleplaying restriction of having an extraplanar creature angry at you for gating it in is just that. It's not enough of a "hard" restriction to balance the spell. A reasonably smart player will gate in a known or named creature, and most likely will gate in a creature of sufficiently similar alignment that those creatures will not resent their service to the caster. For example, an evil caster will summon a balor or infernal who enjoys the opportunity to crush powerful good foes, while a good caster will summon a solar or other divine servant who similarly has an interest in combatting evil foes.