- it is explicitly (or at least formerly) not considered a currency
- it is centralized (the company can freeze accounts if it wants, create more coins, or be sued)
- it's major use case is for inter-bank transfers. So if Bank A and Bank B was to exchange currency x for y, they will use XRP in-between. But this gives no value to the currency itself, it is just used as an intermediary. Is it conceivable that Ripple the company will not have enough XRP for these internal bank transfers and they are going to have to buy them back from the public??
So it seems that XRP has no value outside its use by the company Ripple. Is anyone actually using it for commerce or any other reason? It is not considered a store of value like bitcoin (in any case one would want something decentralized.
Many of the true "crypto-enthusiasts" are ideologically opposed to holding Ripple due to its centralized nature. However, many of those who buy Ripple are investors that are only interested in its potential rise in price. For them it doesn't matter how you classify Ripple, its utility, or its stance in regards to traditional crypto values. If they think that the hype will bring the price up, then they can make a profit off of it.
Also, Ripple is very well a currency. It can be: a) exchanged for something of value, b) exchanged for other currencies, and c) is limited in its emission (at least so far). If the currency is USED as an intermediary - then it is used for something, aka useful, aka it has value.