Some plants the flowers are very pretty, but the whole plant isn’t practical to be kept indoors (e.g. roses), and they don’t necessarily flower all year round. If someone has a favourite flower or favourite colour of flower, it makes them feel special when someone thinks to buy them for them (they get a flower they love to look at for the next week, and they know that someone cares about them enough to buy them flowers, and keep the knowledge of which like).
Some plants the flowers are very pretty, but the whole plant isn’t practical to be kept indoors (e.g. roses), and they don’t necessarily flower all year round. If someone has a favourite flower or favourite colour of flower, it makes them feel special when someone thinks to buy them for them (they get a flower they love to look at for the next week, and they know that someone cares about them enough to buy them flowers, and keep the knowledge of which like).