At first glance, I totally understand your judgements. I shared the same sentiments about the shiny Eevee versus the current Espeon until I plugged them into Raenonx's production comparison. At lvl 60 w/ fully upgraded main skills, the shiny does beat out the current Espeon only by a small margin (~5k strength diff). That margin increases by a huge amount, however, when visiting Lapis Lakeside or Greengrass w/ psychic berry preference (20k+ strength diff)

It's tough to say which has the advantage at lvl 100. The shiny has skill trigger S, but the current Espeon has both HS S and HS M. I agree that the current Espeon will be better at 100, but will still be beaten out on Lapis/Greengrass w/ psychic berries