From a GM's perspective, they also let you keep the field even between the entire group of PCs. You can be more generous with people who are not as naturally good at
That said, as a GM sometimes you have a group of experienced players who don't need or want the nudging, or you prefer to reward people according to their effort and skill, or maybe you'd rather not risk Defenses and Initiative going up much higher from normal, or perhaps do not want to actually bother with all this Arc structure crap that makes you think way too much in advance.
Those reasons, as well as many others, are good enough to consider houseruling the way that Genre works. There's as many ways to do this as there's problems that you personally have with the current model. The three houserules below are made with different kinds of games in mind, and would be a good starting point for further modifications.
Fair and Balanced
Award Genre after each Operation depending on how difficult it was, as if it were XP. Points never reset, but no longer give a bonus to Defenses or Initiative. After around 15 XP everyone gains a new Power plus a static +1 to Defenses and Initiative. This method basically erases the need to hand off and track Genre individually and to plan out Arcs in advance, otherwise it does not change much about how both work in rules terms.
Gods of War
Award Genre as normal. Points never reset, but there is a hard cap of 10 non-Temporary Genre and Points earned beyond that limit are temporary and will vanish after the end of the next Operation. For every 10 (non-Temporary) Points spent a PC gains a new Power plus a static +1 to Defenses and Initiative. This method trades the usual benefits of Arc Progression for placing them in the hands of the Players. In addition, the easy stacking of Genre will let PCs regularly resist and overpower most threats on the ground, and making short work of anything they deem threatening while out in their giant robots.
Against all Odds
Award 1 Genre per Operation, and another for remarkable roleplaying - preferably of the variety that sets a considerable setback on the PC. Meant for the harder games out there, since Genre Points only come after a victory or when PCs complicate things for themselves, and only in low amounts, it is recommended these games don't focus too much on combat and have an Operation every few Episodes instead.
Again, those are only the three I had in mind as I made this post, there's other ways that help other kinds of groups and games more out there. Genre is one of the (if not the) softest rules in the game, and you can bend it around without breaking down the game into a terrible mess, so don't be afraid to play around with it if it does not satisfy you.