I'm kinda gonna lean on the other side here. I'd love love
love to play without energy rules, but honestly, there does need to be a cost system in order to give forth a sense of "use what you have over time to play and enjoy the game". Mainly as in general the game isn't the original SG where the story is slightly more vague and you're just playing a fighting game.
This game is more leaning to RPG mechanics, so, you can't expect people to run willy nilly because then people can invest far more time to optimize their teams and literally lead to the meta and other properties of the game to be literally obsolete. AKA, you could have a total maxed out team in one weak for example because all someone did was grind dailies in one day, and the game didn't even release a new counter / meta to keep things balanced.
Now granted of course, from your perspective, Prize Fights are definitely something tough, we get it. But it's not something that has to do with the energy bar, if you gotta stick to your team of Filia's, that's kinda on you because you're allowed other areas to grind for exp too. And of course, on a off hand notice, I would pin that issue more to bringing back the old Arena / Action mode (I think it was? I don't recall the name as I played the beta loooong ago) so you can fight and get exp proportionate to the participating fighters.
Like
@Tayla_The_Potato and
@Snow have said, there does need to be some sort of balance here. I dislike the wait times myself, but that's why they instituted those energy chargers on the upgrades screen so you can recharge quicker. At this point, it's either no energy bar but ads every so often, or energy bars and HV / SG makes some small revenue over the theonite purchases aside from the relics. I for one, am fine with the energy bar because then I can always just switch fighters and maybe try fighting the lower tier (Because of course there's also more than 1 tier than just gold in Prize fights) for my lower leveled fighters. Even if it's an incentive to pay to recharge, really, it's a small price when you can just upgrade the recharge timer and have less time waiting anyway.
In the end? If you just wanna dive in to the fights and be done with it, stick to SG: 2nd encore! It's not like Mobile with stats and status effects, but it's the core SG fighting game we love.
If not? Welcome to the world of mobile gaming, the game (like many other mobile games) itself needs to stay within bounds of what customers can use in order not to fully progress faster than the Devs producing the game's meta, as well as have some sort of stable way to get revenue (I.E, rolls based on chance). Really saying, it's annoying at some points, but I'd say after building up your teams and sticking around a bit, you'll be there in no time!