Coliseum is for r10.
If you're not into r10, it's not for you. If you want r10 but you're not a whale? Well, the top 10 players get 1000 tokens while you get 50. Congrats, you get 5% of their progress. So you want r10, but you won't get it.
Do you get anything else?
Well, when you finally get your marquee toon, you get to skip the lower gear tiers. But if you had plenty of gear just sitting around doing nothing, then... you get nothing of value.
The g1-g11 is worthless. The r10 progress is so small as to be worthless. There is nothing of value for the loyal players who have had a chance to stockpile gear.
If you're brand new, congrats, you get a bunch of free low-tier gear + some kyros. If you're midgame, you get a bunch of free low-tier gear so that you can spend what you do have on old toons. Great that you get that Iden Verso up to g10, isn't it? If you're a whale, you get good progress on r10.
But no one else gets anything. It's a boring game mode with no rewards that actually matter. I'm certainly not motivated to play this.