People think Sombra's a lame villain from lack of screentime and dialog, but it seems to be they've only seen the episode once, because when Sombra does appear the scenes are as epic as A Canterlot Wedding and he is even more malevolent, dark, and imtimidating than Chrysalis. Also while Chrysalis only got a presumed death (unless you view comics as canon), Sombra was KilledOffForReal, and in a spectacular way, as I mention on my Top 90 villain deaths review Sombra is number 3.
All in all, my second favorite villain after Chrysalis and this picture is amazing
I agree with you. Not every villain has to have funny lines and a whacky personality. Sombra is more of a looming, terrifying threat than an antagonist for the heroines and heroes to interact with. Just like Sauron, he is a very iconic villain and he has even less presence than Sombra.