DLC released every few months which adds new features or mechanics is perfectly fine. I'm not sure if its still the case by Skyline's team used to release DLC in two parts, a bit for a free and an extra bit you had to pay for, they do it really really well.

Generally there's a stigma around DLC cut out of the original game to be sold as extras on top, See anything EA / Ubisoft crap out.

The issue is that DLC is an umbrella term that applies to both exploitative micro-transactions as well as what used to be known as "expansions"