CapnZapp
Legend
Why are you excluding their major feature?But what else can Wizards do to a degree more then the other casters out there besides their spell flexibility?
In other words, why wizard instead of some other caster. (Outside knowledge skills.)
It is precisely their flexibility that provides a reason for playing them!
Traditionally (and especially with Monte Cook era adventures) you needed a Wizard to cast that highly specific spell once in a while.
Even in 5E you can't replace that role in the party with a Sorcerer or Warlock. They can't afford to pick spells they aren't using themselves.
(Lore Bard maybe)
In 5E this aspect is much less pronounced, almost to the level of being eradicated.
So in these cases a Wizard is not strictly needed, and if DPS is a concern, bring a Sorcerer instead. (Or forget casters and instead bring melee DPS monsters)
That said, being the party Wizard can be a lot of fun. Especially if the party already contains a blaster caster, since that takes away the pressure for you to focus on damage dealing.