While you may want to just attack with your creatures, it does give them a form of haste that can generate value
The Moxen were iconic and expensive cards at the time they were banned, and removing them from the card pool was intended to combat the notion that Commander is a prohibitively expensive and inaccessible format
Though tappers are just useful cards to have around, the support of stun counters and consistency of it's effects make it a legitimate archetype to build decks around
However, being able to hit any permanent card and give us value later are both two relevant upsides
For example, cards like Nullrune, which can permanently remove non-attack action cards, might provide more consistent value
As soon as you do so and either have an ascend card on the battlefield or resolve an ascend spell, you earn the city's blessing