This would be the last place I'd upload anything important. Once that URL/password get out, whatever "secure" file I've uploaded is exposed forever.
That is true even if you can delete the uploaded file. Once someone else has seen it you no longer control distribution.
That said, you are right to distrust file transfer services by default. They are in a position to mess with you in many ways.
With a file stored on the blockchain, I remain continuously and permanently vulnerable to a data breach or any other loss of secrecy control. The moment that link/password combo is compromised, that file is permanently public.
Now, you could argue that the moment a file is briefly public, it can be downloaded and thus is outside of your control anyway, and you'd be correct. But the case I'm more specifically thinking of is trying to send a large, reasonably secret file through email. You can't attack 1GB to mail, so you upload it somewhere and send the email with the url/password.
If you use Firefox Send, that file gets to its recipient, and then shortly thereafter, the link becomes invalid. If I use this service, that link stays valid forever. If my company's email archive is then later exfiltrated by a hacker or disgruntled employee, that secure file in the first case remains secure. In the second case, it's now compromised.
This doesn't invalidate certain uses of your service, but to not mention anywhere on your site that uploaded files will remain available irrevocably and forever is negligent.