Importance: Lets just remove that position and see how it plays out, like a red card in soccer.
If no center, ball doesn't get snapped, QB has to take it from the ground. Defense (fastest guy) lines up right over it and has the shortest distance to the QB. Every play has QB getting killed as he backs out.
If no tackle, offense runs away from that side, or rolls the pocket away from there. Would be tough, but could still function.
Center is a more important position.
With that said, why are Tackles both paid more, and drafted higher? It is much harder to acquire a 330lb massive strength monster who has an anchor, and has the quickness to stay with LBs to 1T's when they will usually end up being on an island and not able to get help without sacrificing a receiver; than it is to find a Smart, Huge, Strong, guy who can snap a ball, but who can always slide coverage his way to help him slow the rush.
I can find 10,000 QB's, but not ones that are NFL talented.
I can find 20,000 LT's, but not ones that are NFL talented.
There are just more guys built to play C than there are guys built to be all-pro LTs.
Although with the new rules, LT isn't quite as needed as it used to be. Teams needed that guy to keep the QB from being blindsided and "out for the season". Eventually teams will realize the new rules that keep the QB safe make the athletic LT less needed as the DE can't fiy by the LT, hit the QB and land on him because his sack just got turned into a 15 yd penalty. Deacon Jones, Harvey Martin, and several others wouldn't even get a game day paycheck if they played in todays game.