Was going to post a thread about this myself, but I'll add to this instead.
It's extremely frustrating when you're hunting for anything remotely rare, and going 2/3/4+ hours between spawns (I managed to go 7 hours - a morning, day, night, morning, day in game cycle - without finding a trapinch or a sandile at route 111 desert, and then when one finally appears your client crashes when you click on items. Now I'm all for keeping rare pokemon rare and limiting how many people are able to find epics of these pokemon, but when you do finally find one and the client crashes and doesn't respond until you get logged for being afk it's extremely demotivating. I've already lost a trapinch and a shiny geodude due to ending up back on the login page before the items menu appears.