I'm not sure whether removing the % would help, at least when it's replaced with what you need to roll then. Everybody knows that in Parcheesi you need to roll a 6 to start, but few don't get frustrated when they go long spells of not rolling that 6. In German the game is actually called "Mensch ärgere Dich nicht" ("Don't get angry").
Additionally, if the game automatically displays the probabilities, you don't need to be as familiar with D&D rules -- the game is doing all the Maths for you. Human brains may be notoriously bad with understanding probabilities, but the numbers itself are understood (higher chances are obviously better). It's tricky.
I'm new to DnD and I have to say that the combat is one of the things I'm having a hard time understanding. Like you said, how can you miss a hit when the enemy is in front of you? Or the game telling you that you have 25% of hitting the enemy that is standing in front of you? I used a super power spell and I was positive it could hurt the enemy and I get "Critical Miss". Seriously?
You have disadvantage on any ranged attack when an opponent is TOO CLOSE to you (a spell is a ranged attack). You get to roll with a 20 sided dice twice, but have to take the worse roll. This naturally also increases the likelyhood of a critical miss (getting a 1 on either roll). This is the explanation why they're doing it that way:
https://roll20.net/compendium/dnd5e/Combat#contentRanged Attacks in Close Combat
Aiming a ranged Attack is more difficult when a foe is next to you. When you make a ranged Attack with a weapon, a spell, or some other means, you have disadvantage on the Attack roll if you are within 5 feet of a Hostile creature who can see you and who isn’t Incapacitated.
