Even when I have a character with Tumble (and I have taken it often even as a cross-class skill), I always prefer not to have to use it at all, in the sense that I try to move only if I don't provoke AoOs - eventually withdrawing or takinf 5ft step - or otherwise don't move yet until there is a safe path.
When it is really necessary to Tumble, I do it and hope the skill it saves me, like a "parachute".
Mobility is like having a "second parachute" for those times when the first one doesn't open... Clearly if you have high ranks on Tumble, taking this feat means you really want to be careful with prudence. But if you couldn't afford high ranks, perhaps because it's not a class skill for you, it can help quite a lot.
About Dodge: +1 vs a single enemy is not a bomb, but every stacking increase to AC is IMHO always welcome. I don't think it's so annoying to "choose" the target every action, more or less it's always the enemy you are attacking yourself at the moment and the DM can assume that UNLESS the player specifies otherwise; when you are not attacking anyone, it is usually the closest enemy who is attacking you, or the last enemy you attacked, or the one you are e.g. tumbling away from...