A few months ago I asked one of my gallery directors if he thought I should try adding a glossy resin coating to my paintings. He emphatically told me "I hate that stuff"!
Turns out he contacted the main chemist at Grumbacher Artist Paints who told him that no matter what anyone claims, resin turns yellow very quickly. It also has other distressing properties that make for problems over time. Ultimately, collectors are often contacting the gallery asking why their painting doesn't look the same. Returned art required exchanges or refunds.
I was glad to hear about the technical issues. But my own thoughts are aesthetic. It appears that clients often make superficial judgments about quality based on surface sheen. In effect, it seems that comparisons are made to the glass of a smart phone or finish on a fine automobile's paint job.
I want to direct people's attention to a painting's more essential aspects. Therefore I've been making my surfaces quite mat. I like this aesthetic. I hope others will too.