One thing that has been annoying me lately is that once wsjtx has sent RR73, the TX stops. By the time you get that next one out, it's too late and the DX station is working someone else. I've lost many a QSL as a result, because some operators expect a 73 or they won't log you. Clicking tx again results in an involuntary CQ if you're not careful.
I know there is an RRR option, but that's not a 73. It just draws out the QSO and the OP is still expecting a 73 and he will not log you until he gets it. (Not all ops, but some).
I log everyone if there is an exchange of signal reports. Waiting for the 73 is just not realistic on FT8 in certain conditions and especially in a pile up, someone is going to jump on top of that 73 anyway. The person working the pile up "should" be experienced enough to realise this, but still, I get many who still won't QSL.
Conclusion, it would be great if 73 could repeat say a maximum of three times until both parties are satisfied the QSO is complete. Of course, it wouldn't be necessary if people were not so upset about not getting their 73 and refusing to QSL.
This behaviour also happens after 15 minute SSB QSO's too. I've received a "not in my log" back from them, because QSB closed in before we could say 73. Wow!