Just like fashion in clothing, architecture, and interior decor, plants come in and go out of style. Some of this is due to new plant introductions which are hybridized for specific characteristics.
Some examples of this would be ENCORE azaleas. They are hybridize to bloom more than once annually. They have all but eliminated the demand for certain azalea cultivars. KNOCK OUT and DRIFT roses are another example. The demand for hybrid tea and floribundas roses has been drastically reduced. The newer hybrids are much more disease and insect resistant and they bloom much more.
Some plants simply just go out of “style” for a while and then come back into popularity. A good example for this right now is Emerald Arborvitae. Forty years ago it was a popular landscape plant, dropped out of sight for a while and now is more popular than ever!
The moral of the story is, never give up on the plants that were in your grandmother’s yard. Next year they might be HOT!!