More ways to spend influence without having more influence income is not a bad thing. If you just build everything every game then every game is the same. Selecting which ways you spend which resources is what makes subsequent playthroughs potentially different. That's why Traditions stink, because they're just generically good, generically less good, and generically bad, and you pick 4 or 5 of your 7 the exact same every game because most of the time you only really care about two of them and the rest is filler.
The problem is that spending 55 influence on an espionage mission inherently makes the mission completely useless. For one, that's not really something that Influence is supposed to be gating. Espionage missions get you stuff like information, techs, minor diplomatic effects, maybe some military advantages... 55 Influence gets you most of an Outpost. It gets you an Orbital Ring. Four of them gets you a Galactic Community motion, and three of them a Habitat. Or you can advance a pre-FTL species by a single era. Not even remotely worthwhile.