This solves many but not all issues cos maybe the developers are also worried about filling up the receiver’s relay storage (especially in multi-device mode) or overloading relays which might have limited bandwidth by sending too much network traffic, if this is something the developers worry about. (I guess the relay storage issue could be solved with some smart automatic deletion logic.)
I think it would make things worse from both the convenience and privacy perspective. It would turn the asynchronous app into a synchronous one which is much less convenient because not everybody is constantly online and it also potentially exposes your IP address. (While the offficial DC position seems to be “just use a VPN to protect your IP address”, some of the developers seem doubtful that this is sufficient when using iroh and so far none of the developers have stated for the record that a VPN is actually guaranteed to prevent iroh leaking your IP.)