The evolving wilds allows for "deck thinning" while playing a game. Think about when your playing a game and you have plenty of mana already out and you go to draw a card and you draw another mana, deck thinning tries to help prevent that. The only down side to using evolving wilds or something like terramorphic expanse is that the land enters the battlefield tapped, but this isn't always a bad thing depending on the situation or whats in your hand at the time. The main point is to thin your deck of mana so that as the game goes on you can draw more non-mana card to play.
There is no thinning with a wasted slot/value/card. You said it yourself with plenty of mana. Evolving wilds isn't going to do any good with a empty hand while top decking it. An extremly fast aggro deck that runs out of steam and top decks evolving wilds when a spell would be much more handier.
Evolving Wilds is only good for 2 things, either getting the land you need or landfall trigger ability. Fetching for a land you need isn't necessary here because it's all the same color and no landfall triggers. You are running a 1.3 avg mana drop, I don't think bringing the avg to 1.4 to 1.5 by adding slot/value/card with a spell instead will slow you down.
True that drawing an evolving wilds doesn't do you any good with an empty had but neither does drawing a basic land, which could easily happen in this fast deck with such a low mana cost. At least the evolving wilds pulls out two mana cards from your deck in that case rather than the basic land just pulling out just one when you already have plenty of mana. That way there is a slightly higher chance for the player to draw a non land card on future draws. I understand that this many not be necessary in this deck but thinning the deck of mana can be a useful tool in many decks and I don't see it being a bad idea in this case. Ultimately, I was just pointing out that the reason for the evolving wilds in this deck is to reduce the Plains in it to increase the chance of drawing something useful.
This deck will run out of gas. Quick out of the gate and sputters. 1.3 avg drop with 0 evasion. No matter what card you are looking for it won't win many races. Nothing in this deck for a finisher. Scrying and drawing to set up what finisher? Ok 1 Abbey with creatures that do get bigger. Again no evasion, flying, first strike, vigiliance, double strike, nothing. Just the potential of mediocre creatures. Hoping to have your creatures survive on 8 protection from color spells to win the game?
No matter how much you think Evolving Wilds is making you think, it's not really helping. You could even drop 2 Evolving Wilds and replace that with 2 Spirit Mantle all without hurting the curve. Thus making another finisher.
I completely agree with you on that, this deck is going to experience running out of gas due to such a low mana cost. I do think that the
evolving wilds although not really helping the deck, by no means to they really hurt it either though. I like the idea of adding
spirit mantle to the deck very much as it revolves around the use protection and stays in the field rather that just one turn. I think that is actually a really good add to this deck. What do you think about possibly running with two
Westvale Abbey cards? Increasing the chance of drawing it and getting to use it and that can be a hard creature to deal with, at least in my opinion. I've personally had difficulty facing off against that card in some games once its a creature and seen it be a turning point to win games.