I agree. About a year ago we hired a new person at work and he immediately started looking for ways to improve anything and everything. The problem is, nearly everything we had that wasn't optimal, was still actually "good enough" for our needs and usually included some complexity that wasn't obvious at first glance. He ignored our "if it's not broken, don't fix it" advice and every single time he tried to improve something he ended up breaking it or making it worse.

Sometimes a simple but sub-optimal solution that gets the job done well enough and reliably is better than an optimized solution that includes downtime and requires extra maintenance. I don't think the person offering the advice to leave things alone is always the naïve one.