I think they can look good. Whenever you see the boxer Nicola Adams at an awards ceremony she always wears a trouser suit with a nice blouse and looks fantastic.
There's trouser suits and trouser suits. There's the polyester school uniform type, often issued by firms trying to make employees look serious. Then there's a bespoke men's cut in a nice tropical weight wool, which will set you back hundreds but make you look the business. And permutations inbetween. Difficult to avoid looking like a 1970 wedding photo if you choose bright colours or have the wrong height to width ratio.
I wear trouser suits for meetings at work - as long as they're nicely fitted and not the old style long jacket I think they look very smart. Next do some lovely ones, and if you wear a simple scoop or square-neck shift top underneath, rather than a ruffle or collar, they look even better.
I wore trouser suits all the time when working. They were both smart and practical. I now have a wardrobe full, which I never wear. I must have a clear out!