The D20 solution would just make the Alert feat totally mandatory
I would argue the opposite. Having initiative order based on a d4 system makes the Alert Feat essentially mandatory. As you can see below, Alert Feat is broken on the d4 system...
d4 initiative system: Alert provides (5/4) = 125% bonus
d20 initiative system: Alert provides (5/20) = 25% bonus
Alert was balanced around the d20 initiative system in TT.
