Turn Based or Real Time with Pause, D&D mechanics are balanced around the fact that you might miss your attack and strategies exist within those mechanics which can drastically increase your chances. Flanking, class abilities, stealth, spells for buffs/debuffs, grappling and other strategies can grant advantage (roll d20 twice, taking the better of the 2 rolls) and of course there are ways to force disadvantage (2d20, lower of the 2 rolls) alongside flat bonuses to your attack roll. These are all major factors in how the game is balanced and a computer RPG only speeds up the rolling and calculation aspect.

As to XCOM, I was always fine with misses even when I played it way back on the original Playstation in college. Similarly to D&D you had behind the scene's mechanics which improved your chances (taking a knee, aimed shot, thrown grenades, etc. A solid strategy was to have a soldier with a lot of movement points and high reactions go out and 'sight' for enemies while character(s) with higher accuracy then take a knee and fire at said enemy upon sighting).

I fail to see why players would 'hate' these mechanics other than their own unwillingness to read the manual and understand how to increase the chances of a hit while decreasing their chances of being hit. Story is only one part of an enjoyable game folks, some of us actually enjoy combat that is difficult when you just run in guns blazing vs. understanding the abilities/spells/environment/whatever mechanics which allow you to increase your parties effectiveness while decreasing the enemies. This is what made Baldur's Gate II so popular! Spells that remove resistances/immunities from enemies, combat abilities that improve your chance to hit and/or do damage, mixing up parties to have synergies which allow you to be more effective as a unit than a given character is on his own... Remove the strategies and luck factor and your left with a rock/paper/scissors form of combat 'puzzle' mini-game which I for one find far to boring to spend time playing.