It can be harder and less pleasant to ride, possibly less safe. You may not notice because it has happened slowly, but you might be pleasantly surprised by how much better it can be; or you might just think mechanics upsell stuff you don't need.
As a mostly utility cyclist I'm a lot less fussy about the bikes I use than when I used to ride many miles and time trials, and I "fix it when it's bad enough" rather than keeping everything finely tuned all the time. But anything making the wrong sort of noise, or not doing what I tell it to do when I tell it to do it, does detract from the riding experience.