I don't ever find it more than mildly inconvenient. If you life is so one-dimensional that the downtime is a BFD, you should consider broadening your interests a little.

However, I don't agree that it is a typical maintenance schedule. FFXIV has more frequent and longer maintenance periods than any MMO that I have played in the last 10 years, including GW2, WoW, Lotro, and ESO. I take it as a sign that their back end infrastructure is a bit of a mess, making applying patches or doing database maintenance a lengthy process. It is what it is.