E-vites for Millennial Wedding

I sent out e-vites via Paperless Post for my save the dates. Everyone viewed the email within 1-2 days (I was notified when each recipient opened the email) and had no problems with emails getting sent straight to junk or spam. Even my 90 year old great uncle responded to the invite via Paperless
Post.
70% of our guests are millennials. I personally preferred receiving e-vites over paper invites to weddings I’ve been to in the past year.
I was totally planning on sending e-vites for the formal invitations as well, but after browsing through the forums on here I’ve seen lots of arguments AGAINST e-vites. But mostly for reasons that I already know won’t be a problem, like “old people don’t have email,” or “it could get sent to spam.”
It will save me hundreds of dollars to send out e-vites as opposed to paper invites that will just be thrown away. And this way I can see exactly who has received the invites/it’s easier to keep track of who has RSVP’d.
So I guess I’m just wondering, why are they considered tacky? It saves hundreds and I’m also cutting down on waste. I see more pros than cons, considering it worked so well for the save the dates and the response was huge.