VLAN1 carries certain traffic (CDP, PAgP, DTP, VTP, etc) used by the switches. It's also the default VLAN for all the switch ports. So the idea is not use it for anything else. No compelling reason other than lets keep traffic that has to traverse
vlan 1 from mixing with user traffic and also improves security to a certain extent.
Years ago before there was any great switch hardening (stp, trunking) we liked to change the default management and user vlans to another number for for security reasons. Now it's not such a huge deal as there are other mechanisms to prevent other devices from impacting the network, however, this practice is still carried today....just because we like to change the defaults i guess.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...