VLANs are to reduce broadcast traffic and separate concurrent traffic such as voip and video for example. Multiple SSID create heavier beacon load in the air, otherwise I wouldn’t say 4 ssid is way worse than 2, but if you make even more that can be a problem. Usually 1-2-3 is enough.
Also this “convenient” vlan naming such as 10, 20, 30 etc doesn’t reflect network address correlation and creates chaos later. Way better to plan your network as a bigger prefix, such as 192.168.64.0/22 and split into /24 for different purposes like management, production, wlan, access control etc. And name vlan corresponsive to network number. This will be easier to maintain later when config will grow.
Also always remember about physics and don’t chase better standards just for fun. For example you take cap ax with 2 chains and you put 2-3 SSIDs in there and there’s two chips for each frequency, so if you’ll have production load and guest load at 5 ghz at the same time the performance will drop and split between. But if you’d take Audience which has 4-chain 5ghz on one 5 ghz chip and 2-chain on other, split productino and guest to different physical transmitters and use separate frequency then even though ac is a bit slower than ax you’ll get better parallel performance.
So in my opinion mikrotik is chasing it’s tail making obsolete devices for ax standard while it should run for wifi7 until it’s too late. And make 4-chain devices and multiple-chip devices such as Audience which is really nice as a home-AP.