Umm, did you watch any of the recent England games? Haskell is in the team purely because of his massively physical defence - Jones has talked about how hard he hits. If he just wanted someone with a high workrate he could put Robshaw there, which he did in the 3rd test against Australia because Harrison wasn´t providing the physicality he was looking for from his no. 7. I have never seen Harrison put in the hits like Haskell does (that was Haskell smashing Pocock in the first few seconds of the first test, btw). Harrison however is much better over the ball, and more dangerous ball-in-hand than Haskell.
Ewers is not a better lineout option than anyone, except perhaps Billy Vunipola or Steffon Armitage. Ewers hardly ever jumps for Chiefs. Haskell however is a perfectly adequate line out option, although he is so crucial at the tail of the lineout that Robshaw is normally the backrow option. Ewers is decent at the breakdown, but he isn´t fast enough to get there as a no.7. Again, almost anyone could claim to be more intelligent and a better handler than Haskell, but I don´t know what tactical means in terms of a backrow forward.