Personally, I am stridently against this. I am a light spender. (Been here going on eighteen months, spent maybe $30.) I don't have a top class deck, I have a win % of like 20. I lose against everyone. But at least with the system as is, I can sometimes be matched against other people who aren't top tier. Still don't win, but it's generally closer. Including letting me last at least ten turns, so the matches qualify for those 5 of 7 events...
Now, if I were to be paired off only against other spenders, I think that would change a lot. My win ratio would stay about the same, minuscule, but I'd also be likely to lose faster, and as a result, miss out on events. That, in turn, would likely make me completely give up on even the once a week game I do now.
And if you're wondering why I paid a little, instead of a lot, well nuts to you. I don't know about you, but being someone who makes a whopping $5 American a month, that means I plugged in HALF A YEAR'S WORTH of my spending money into this game. I do what I can, and even if I want to do more, well, too bad for me. I wanted more than what I could get as a freeplayer, so I put in what I could afford. (Technically more than that...) Put the money in so I'd have enough Gran to get the Ex packs I wanted, plus start my collection off with a box of set 1. Didn't get what I wanted, but I did the best I could. Doesn't mean the file can win easily. I suppose it's possible, though.
So yeah, definitely don't like being forced into a pay-only arena. (Now, if it was an optional thing, maybe. But we don't have the population to divide any further with additional arenas.)