In the end it's all up to you how you want to handle your business, but one of the most downloaded file formats on this website is FBX, since it can be used in just about every software package now. OBJ is also extremely popular. However, one of the most popular formats is the 3dsmax native file format, .max, and Maya's .ma. C4D is also popular on this website. Blender is not quite as popular here as it may be in other markets. People who offer only native .blend files may not see as many sales as people offering other file exchange formats. I would guess that only 10% of people purchasing content here are looking for .blend. However, it is absolutely growing in popularity everywhere, and eventually, it may become one of the most downloaded formats here as well. So it's smart to be ahead of the curve, so to speak.
Bottom line is that if you want to increase sales potential, it's good to offer native file formats for the reasons you mentioned, but you are probably going to miss out on 80% of the potential sales if you don't offer a few more exchange formats with it. Especially .FBX and .OBJ.
That said, I would certainly recommend baking your procedural materials to high res PBR texture maps. It makes your asset far more appealing to potential customers. However, I personally offer both. I will offer a .blend file with Procedural materials, then also another .blend file with PBR texture maps. That actually seems to attract the most potential buyers. At least for me.