To be or not to be complex
That is the question
As with so many questions about IT, the answer is “it depends“.
Complexity for the sake of complexity, or letting ego drive your designs is a bad idea for a lot of reasons. You probably don’t need to prove that you’re smart.
Make your designs as simple as they can be, but as complex as they need to be.
Network engineering is never as simple as that one power switch in the image above, but just try to minimize how many nerd knobs you twist. I can see engineers arguing over an MTU of 1480 Vs. 1481 or playing with some timer for an hour to shave a nanosecond off some convergence. Please.
Where things get really fun are with VLANs and security.
Check this out:
I grabbed this from Cisco Communities (credit GiulianaA from a post back in 2005). That is a real, production configuration. 64 VLANs on what must have been 2950 switches back then. That’s more VLANs than they had ports! Obviously they were using VTP and trunking these VLANs everywhere. I didn’t read into the particulars for this case, but I can’t see a need for such a configuration for any application. Certainly not to trunk all VLANs across all switches.
Opposite opinions can occur too. I work with people who don’t believe in segmenting traffic at all. Not even separating voice and data traffic. They don’t understand networks other than 192.168.1.0/24. But then, they are not really networking people. I got into a debate once with a colleague over the phone:
Other guy: “These guys were sure over-sold”
Me: “Whatcha mean?”
Other guy: “All that fiber”
(I was unfamiliar with the customer)
Me: “What fiber?”
Other guy: “From the core switch to the VM host server. They have two fibers going to it.”
Me: 
‘Nuff said.