Why is it so difficult to manage VLAN’s with routeros ?
Taken an example from Zyxel attached, way easier.

This looks more like a switch config - routers are very different.
SwitchOS has similar style of VLAN management.
RouterOS has very flexible options and management interfaces (winbox, webfig, cli etc), and GUI’s like this are very restrictive to keeping that common style between the management interfaces.
The beautiful thing is - you could create a VLAN table like this and manage your switches by creating the GUI yourself, and translating to the right command in the background and hitting it via API!
Zyxel is typically used in homes or very small business. Then you want a very easy set of features so that users doesn’t screw up.
Fortunally Mikrotik is more leaned to (semi-)professional use, having both CLI and API for manage thousands of devices.
What a bit of a failure is that the CRS1xx, CRS2xx and CRS3xx has very different VLAN setup and configuration style.
This isn’t that much harder with RouterOS. Here is the equivalent:
/interface bridge port
add bridge=bridge interface=ether1 pvid=640
add bridge=bridge interface=ether2 pvid=2
add bridge=bridge interface=ether3 pvid=10
add bridge=bridge interface=ether4 pvid=10
add bridge=bridge interface=ether5 pvid=12
add bridge=bridge interface=ether6 pvid=12
add bridge=bridge interface=ether7 pvid=12
add bridge=bridge interface=ether8 pvid=12
add bridge=bridge interface=ether9 pvid=10
add bridge=bridge interface=ether10 pvid=10
add bridge=bridge interface=ether11 pvid=2
add bridge=bridge interface=ether12 pvid=2
/interface bridge vlan
add bridge=bridge tagged=ether2,ether12 vlan-ids=10
add bridge=bridge tagged=ether12 vlan-ids=12
add bridge=bridge tagged=ether11,ether12 vlan-ids=300
add bridge=bridge tagged=ether2 vlan-ids=640
Note that on whichever VLAN the switch itself is supposed to get an IP on (management vlan) you’ll have to add “bridge” itself as another tagged port in order to still be able to reach the switch management interface after enabling bridge VLAN filtering.