Yea, I'm very surprised they haven't just copied MTG as close as they can. Just make arena a proxy of mtg 'draft', where the 3-4 most recent sets, plus core, are available. Balance the offering rates so you have like 1/3rd core, 1/3rd most recent xpac, 1/3rd other two xpacs. Or, if they want to promote the most recent set more, and it's big enough, 30% core, 50% recent xpac, 20% other.
Or, as others have said, do a sealed style. Where you know your entire pool and can build a deck around that.
I can't tell you how many times I got offered a really cool 'synergy' card early on, but couldn't take it cause I had no idea if I'd get the cards to support it in the rest of the draft so I passed on it then kicked myself when the support cards showed up later. If I knew everything that was going to be offered, and saw the support cards, that would have been great.
So many easy ways to fix arena and make it interesting. I really don't understand what is going on in that dev team that they have to wait till there is a huge public outcry about it before they even put a bandaid.