discord is community based, there is no use for unique usernames. changing away from discriminators puts up at least two new issues:
1) it will still be hard to find people since names will have to be longer or changed slightly because they got taken (for example "john" to "jonn", and it gets worse as the username length increases). usernames will become longer. you will still have the problem of two names, which you said is the reason you dont like display name + discriminator.
2) there will be a pretty clear separation between people who were on discord for a long time and those who are new
i also believe that discriminators make discord unique from other platforms andby removing them you remove part of discord's identity