The supposed lack of effectiveness is a product of low numbers deployed vs. an enemy that has superior numbers not just in the air but also on the ground.
It would've made the life of the armored units a bit easier. Quirk being - plenty, plenty of those is needed to cover thousand miles of the front line, that not just means they eat into the production of tanks and SP AT vehicles, but also that they need fuel, that precious comodity.
The self-propelled 30mm should be a good addition, perhaps erstwhile on the Marder chassis as a single barreled gun - does not eat into heavier hulls' production, and will use less fuel, while the cross country mobility is better than with half-tracks.