There are loads of classics available for free on Kindle, so you don't have to pay a fortune for things.
Also, they're great for those with visual impairment. I haven't worked in libraries for a couple of decades now, but I wonder if eReaders have affected large print publishers.
For the sorts of books you get as paperbacks, eReaders are fine. For books like art exhibition catalogues, I want the actual paper version (no idea if any have been made available for eReaders, anyway.)
And eReaders are never going to replace the 17th century book I have which was owned by an ancestor, or the poetry book I have which my grandmother illustrated with her own watercolours, or the copies I have which have been signed by the author, or the ones which have sentimental value because of who gave them to me, or which are falling apart because I have read and reread them so much.
Also, I have a tendency to go on holiday to places where there may be no electricity, in which case a book tends to be far better value, as I don't have to worry about recharging things. I read Tom Jones by candlelight in the middle of a jungle - a Kindle wouldn't have been any use to me there, even if they had existed then.
There's room for both in this world.