It is important to listen to that advice which is not nit picking. Correct design and prototyping is extremely important and spending too much time creating deep object models wastes time and you end up never releasing even the prototype because the design is too complex. Keep game design docs simple and the code equally simple and design as you go. Take an iterative model and don't over analyse. Definitely not a nit pick and possibly one of the most important pieces of advice you'll ever receive! I am sure many others will agree...
Your original post asked for general advice on how to code an RTS with modern technology and in this respect the advice to not over design the solution is very useful.
Even I agree. I went the route of XNA working on my own engine type code instead of picking an engine. A year of hobby-time pursuit later (along with full-time+ job and being a good father) and I've got lots of cool building blocks for a game: a layered sprite hierarchy, some cool dynaimc controls, particle effects, shaders, some simple networking code, etc. But I still don't have MY GAME! >.< And this is after years of being a professional developer, so my time was mostly productive.
I was able to use my engine to crank out an entry(Toys: Guardians of Innocence) for the 2014 Game Jam and that was lots of fun, but I was crazy impressed with what other people did with Unity. Even though I was really proud of my entry, I wished I had been learning to use Unity over that last year, but it was still an awesome experience. Since then I've been taking it easy and messing around with Unity.
BigBadBeef, you're a little bit defensive. This is one of the nicest communities of internet personalities I've had the privelage to be a part of. Sometimes people can be a little blunt, or a little harsh, but nearly all of it is awesome advice. Know that for the most part the community is supportive and means well. /hugs