A few points to consider:
1. Yes, wands of lesser vigor are more gold-efficient than wands of cure light wounds.
1.5 Wands of cure light wounds have several other advantages, however:
1.6 As discussed, they are usable by more classes
1.7 They work 5.5 times as quickly. By the time you're level 6, wands of cure light wounds aren't combat healing any more so the "now" bit is irrelevant. However, if you're sixth level and your fighters need to heal 45 hp after a gruelling combat, getting it done in 8 rounds leaves you with plenty of room on the min/level spells. Getting that done in 45 rounds means those min/level spells will be running out by the time you get to the next combat or will not have fully taken effect by the time enemy reinforcements arrive.
WRT Mass Lesser Vigor, it's a useful spell but it suffers from the problem that:
1. It's one hit point per round. In combat, that's not so special by the time it can be cast; out of combat, the multiple targets will often be wasted.
2. Compared to mass cure light wounds, it's better if you want to heal the party after a fight, but mass cure light wounds is not used to heal parties after fights. Mass cure light wounds is in-combat healing.
2.5 Mass cure light wounds is also a very weak spell for 5th level. The only reason it's ever cast is because it doesn't need preparation and consequently can be substituted for a good spell that's not useful at the moment. If it had to compete with flame strike and spell resistance on its own, it would never get cast.
On the whole, I don't think the vigor spells are overpowered. They're useful and powerful, but they have their drawbacks. If you worry about power creep, the only one you need to be wary of is lesser vigor (because it makes non-combat healing slightly cheaper). It can be dealt with by either including more multi-part encounters or by moving it to 2nd level.