I think it is really interesting that that is the perception of most people, since I basically never loose concentration. Maybe I just don't notice? Or maybe I play way more defensively than other people? (My combats also take very long...)
Idk. But a surface like I described for fireball (on the start of your turn/ when first moving into the effect) would add one saving throw with DC10. The basic fireball gives you a DC between 10 and 14. I can see that that is problematic. I think a solution would be to remove the DC10 floor for concentration saves.
If it always is damage/2 as DC, then fire would give a concentration save between DC1 and DC2. Basically you can only fail with a natural 1, so 5%...
So that would basically limit the effect to just dealing damage, without breaking concentration
