Yes the random rolls tend to miss multiple times in a row, wich is statistically improbable and very frustrating (especially when you got a big "critical miss !" when you need a 2+ to hit...
).
As the OP said, sense of "avoidances" by enemie may slightly alleviate the feeling of the game basically spitting "you suck" to you constantly.
Like missing the enemy by 1-2 margin being either "blocked" or "parried" feedbacks instead of miss/critical miss should help getting a better feel of what's going on, instead of the binary system we got here.
But the way of deviating the ruleset by lowering AC/buffing HP is no good IMO ; as you said goblins being bulletsponges will not alleviate the fact combat will be twice as long.
Better introduce "brushing hits" when target is damaged for a fraction of the regular roll, like missing by 1-2 will deal half damage or something like that. Far less frustrating when you miss with you 2-handed fighter than now, but it could lead to player issues as well (enemy will damage players more as well, where any lost HP can make a big difference in combat outcomes).
Also when AI got improved I expect to see different behaviors happening in combat, like goblins starting to flee after being severly injured, with maybe a "willpower" check for nearby allies, wich may trigger fear and other reactions to being hit/burned/slaughtered to bits, as well as the opposite (ennemy pushing their advantage over you when they feel they are winning).
