Flowers and baskets of fruit can also take up precious space around the patient. When undergoing treatment there is a lot of equipment around the bed, and if people are in for a while they have all their own bits & pieces too - everything in an already limited space. And having to ask visitors to take large items home each time they visit can also be a pain.
Girlfriends are an unbelievably hard species to buy presents for. If it's a new relationship, they're going to go for "Oh! Just get me anything!". As opposed to if it's a long term relationship, when they're instead going to state "Oh, just get me anything!". You both know, that's not how this is going to go.