This is generally seen as the main flaw with the games core design. Most other currently successful trading card game (mainly Hearthstone) with mana resources have gone the route of providing a consistent source of resources per turn. This approach does significantly reduce the variance match to match and leads to a lot less of the "feel bad" moments of getting flooded or screwed.

That being said I personally find the variance that Magic has when it comes to mana resources to be more interesting than the alternatives as most of the newer card games have abandoned the idea of having mana resources(lands) in your deck all together. I think the lands are one of the main things that makes Magic an interesting card game.

One interesting alternative to lands was from the World of Warcraft Card game (spiritual successor to Hearthstone) which allowed you to play any card from your hand face down as a mana resource. Although they completely did away with this in Hearthstone so they could limit the deck size and the reduce the number of duplicate cards that were needed in each deck.