Very good thread to be honest I have thought of this increasingly for a long time, the question is this; is Butler the batsman that damn good that his keeping doesn't matter as much at the Test level?
Firstly we need to partly appreciate that for the first time in decades, England have embraced a radical approach when it comes to selections in the modern era, in the past we'd pick a keeper primarily due to his ability with the gloves and if he could bat a bit that was a bonus and that's how it should be generally speaking, e.g Geraint Jones et al. We now don't shy from dynamism or youth, in the limited forms this has worked and done wonders, while such an approach can have its benefits to as we've seen with nations like Pakistan picking bowlers at a very young age, I see this as a positive to giving the likes of Hameed and Pope a chance when it would have been unheard of 10 years ago.
But you have to find that balance, while how wickets are maintained can change and the quality of bowlers/batsman; the way Test cricket is played has not changed, England need to bear that in mind before getting a little too ambitious picking white ball specialists to do the job for them at the highest level, the radical approach is welcomed but they need to think a bit more laterally.
Butler is a special talent and am not against having such a player in the team, but if he is being picked a keeper then that needs to be his specialist skill, there are rare occasions where a select player is great with the gloves and bat, for every 50 or 100 Butler may score, 1 missed chance could cost the team a lot more then any runs he scores ultimately. Evidently his keeping requires a great deal of attention and especially his concentration levels, we need hone these skills; am not sure if he should work things out from within the set up or beyond it but it an area which needs vast improvement, only then can he reach his full potential hopefully