Nothing wrong with feeling the seams in the street while you are riding- unless you are experiencing discomfort because of that. If you are like me, then the more you ride the less the small things will bother you.
If the tiny bumps bother you- you could also switch to fatter tires rather than buying a carbon seat post...if your bike will take fatter tires. Fatter tires definitely give a smoother cushier ride. A cheap test is to not inflate the tires you have to full limit- try 15 pounds less than max.