Why do my roses not have a lot of fragrance?

Sometimes roses just have less fragrance. True. What causes this. Hybridizing.
Trying to make a certain quality in a rose by tissue culturing can give longer lasting, and bigger roses, but can also cause some of the fragrance to be lost.

If you notice Grandma's rose garden has lots more fragrance than most cut roses.
Natural fragrance via nature. Although some cut roses do have exceptional fragrance, like the colors, not red in other words. Sniff them out for yourself at a florist sometime. I always thought pinks had more scent. Go figure.

The other thing that we noticed was cold. Florists' store roses in cold temps to keep them fresh and so do transport companies to wholesalers and so on. When roses are arranged and fresh from the cold the fragrance is usually minimal. Just let them set out at room temperature and what fragrance they do have will be stronger.

So should you stay away from roses that do not smell like roses? No. that is sometimes modern technology at work. They will still last and look pretty.