The difference for me is that Tiefling Fighter, pre-Tasha's, would never even enter my mind as a consideration. The box of playable characters simply didn't include combinations without at least a +1 to a primary stat.
If that is the way you feel I can understand it, but I pity it a bit because it implies the numbers alone seem to mean
that much to you?
With a standard array, for example, you could make a tiefling fighter with 15, 13, 14, 11 (10+1), 12, 10 (8+2). Yes, you only have +2 for your attack and damage rolls, or swap it with DEX if you want a finesse-build with +2 AC as well.
But, by 4th level (which IME doesn't take
very long) you can have a 16 (with a half feat) or 17 even. Sure, you might for a while be +1 behind other PCs, but you have other racial traits (like
hellish rebuke) which hopefully make up for that?
Frankly, even starting with a +2 in my "main thing" never bothered me, or made me feel like I needed to limit my choice of race/class combination. If ASIs were removed competely, you would be in the same boat as a tiefling fighter as RAW.
