ASA 5506 As Router Vs Managed Switch

Hey,

Im trying to convince our company to get a managed switch for our locations vs having the ASA 5506 do all the routing.

Though - im having difficulty finding the benefits of a managed switch vs the ASA aside from the fact that the switch will be able to do PoE.

Were going to be running VOIP/IP Cameras soon at the locations and I have no ports available on the firewall so they want to run unmanaged dummy poe switches :/ (think neat gear etc..)

ASA & Managed Switch can do both of the below:

QoS

"VLANS"

Switch Benefits:

Possible Bandwidth priority to certain VLANs

Limiting Bandiwdth on certain ports

PoE