it may be something as simple as asynchronous development or something to monitor... DS4 is not quite as high LOG as your son is displaying, but at 3, he hated anything to do with drawing, writing, art and from what we seen, DS is very age average physically but mentally ahead. We plan to do an OT evaluation this summer since his motor skills are his weakness and we don't want it to be a weakness that holds him back or frustrates him - I understand from our discussion with the psychologist we consulted (the one we did testing with) that as long as his motor skills are age appropriate right now, the gap between his motor and mental levels is not an issue, but if his motor skills fall below age appropriate, then it is a cause for concern. The earlier you catch specific gaps, the easier it is to correct... but we do have family history with LDs like dysgraphia hence we need to monitor more closely.
However, having said that - as I mentioned, DS at 3 hated, hated anything art, playdough or paper related. I don't know if it was his daycare environment or just he was not ready yet... but this year, he is in a GT school, and now, a year later, loves art and loves doing drawings. He is still age-appropriate for writing but he does not hesitate to draw (trucks, scenes etc - he happy finds the markers and pencils and gets busy, and his art club is one of his favorite activities at school now). I do not know how much is simply being in an environment where they do not push him to finish paperwork, but they expect everyone to put in best effort and simply make it fun. But whatever it is, at home, he is constantly drawing scenes and comes home with drawings that he made and writing they did in school.
And this was the year where suddenly, he really got into Lego and doing the Lego kits himself - even though the kits are for 7+, we just give him the book and kit and he does it all himself now. He used to ask me to help with stickers and now he figured out how to get them onto the tiny legos himself - so the only time we get involved is if there is something he can not do yet due to a motor skill or if something got slightly out of alignment and we need to trace back where it is. Before this year, despite all the blocks and duplos (we have a younger child so we limited certain toys until this year due to choking hazards when she was in the mouthy stage), he was eh about blocks. His sister at 2.5 has been way more into the duplos then he was at the same age.
I try to include less traditional art activities, like finger painting the wall of the bathtub with shaving cream, molding kinetic sand, painting stone tiles outside with water, drawing in sand with sticks, making nature art, etc just to give him an opportunity to build hand strength. We build some archaeological, paleontological, or geological digs out of plaster to extract "artefacts" every few weeks, which he enjoys.
His creativity seems to either be channeled toward weaving an elaborate narrative for imaginary play or building tangible, authentic things, like a shelf or science experiment. I guess I'll keep running with that! Maybe he'll develop an interest in more artsy activities like your son as he matures. Either way, I'm happy so long as the choice is a true choice and not one made for him by a physical impediment.
