I recently (last year or so) did use MVVM on a project that absolutely did not need it just to learn it. Today I'm very glad that I did.
The application isn't extremely complex but my experience now is that I can add new functionality very easily and naturally into it even if I didn't touch the code for some time, much more than in my other programs. MVVM is also very widespread used so you use a design pattern for which you get much help if you have questions. You are not alone with it so to say. ;)
Further I did not add any testing since it was just a pet project so far and today where it is more used than I thought it would be I can easily add testing much more comfortably than I ever could before since ViewModels are just great for testing.
In one of your comments you mentioned an increase in boilerplate code which in my experience mostly comes from the fact that many people publish their properties from their Models only into their ViewModels, duplicating much code in the process. I usually implement INotifyPropertyChanged in my Models to circumvent that. Some see that as bad practice but that's the beauty of it, the design pattern is still fresh and talked about (see Sasha Barbers opinion to this at at codeproject under "Developing Models Using Cinch").
So you can absolutely ignore it for sure and write great software still but I would recommend carefully weighing the advantages you might miss before doing so.