I think the people saying
bankroll is a consideration are partially correct, but you also need to have a decent sized bankrolls to be firing MTT's in the first place. If you are constantly thinking "I need to min cash this or my roll will be ruined" then you're playing WAY too big for your roll.
MTT's are generally excessively top heavy, especially as the field grows larger. Often you are looking at 15-25% of the ENTIRE PRIZE POOL to first place. So if you are going in looking for a min cash of ~2 buyins when there are say, 40-100 buyins up top or even more, then that's a problem.
Let's just take a stupid, simple example and show how important it is to place high.
You play a $10+1 tournament 1,000 times, and it has 1,000 runners. This means the total prize pool is 1,000 runners x $10 = $10,000. For the sake of argument we'll say there is $2,000 up top.
Let's say a decent player min cashes the tournament for $30, 20% of the time, and wins the tournament 2 in 1,000 times. (Yes this is a drastic oversimplification, but bear with me.)
They would cash for $30 20% of the time which is 200 of the times they played out of 1,000 = $6,000 back. They win it 2 times out of 1,000 and win another $4,000. This is $10,000 in cashes, but it cost them $11,000 to enter the tournament 1,000 times, so they are stuck $1,000.
They want to improve their play, so they focus on min cashing a lot to try to bring their numbers up. And let's say they improve dramatically, and start cashing it 25% of the time for $30 (this would be a pretty high cashing rate but w/e). But they still only win it 2 times out of 1,000. So now they add another $1,500 in cashes, to make them profitable for $500 in their 1,000 entries.
What if instead they focused on winning the tournament just 1 more time out of the 1,000? We are not talking a crazy amount. Going from winning it 0.2% of the time to 0.3% of the time. Well now you win $12,000 total on those $11,000 entries. A better improvement than improving your cashing rate by a lot.
Are these numbers made up? Yes.
Should you work to win more AND cash more? Yes.
But the point stands. So much of the money is up top in these things, and it actually becomes a stronger point once you see how much is in the top 3 or top 10 even. This example above actually favors the min casher a bit because we say that getting 2nd place doesn't do any better than say, 100th place.
Focus on going VERY deep, and the money will follow. If you focus on min cashing, you will FEEL like you are doing well, but may actually be losing money in the long run because you never go deep enough to hit those top few spots that actually allow you to have a positive ROI.