Why would you be more tempted to call an all-in here than a standard raise??? That makes no sense. In the second example they have shown even more strength, and it costs you even more money to play your hand.

Okay to see that this is a bad play think of it this way. UTG+1 has opened for a raise, saying I have a somewhat good hand that I like. MP1 then shoves over the top saying he has an even better hand. You ATs does not fair well against this type of action. You are very likely dominated and at most drawing to 3 or so outs (not including your flush, but that is fairly rare).

Now in the original hand I would personally still fold preflop. I might consider calling on the BU playing postflop only if I hit 2 pr or my flush draw, if I was certain original raiser would stack off. But I'm def not calling here in the SB where I would have to play oop. The same reasoning applies as with your hypothetical hand. There is a good chance you are behind already and the odds of you flopping your flush/draw isn't strong enough to call in this instance.