Ugh, the silhouette argument again. YOU CAN'T USE THE SILHOUTTE ARGUEMENT FOR EVERY DESIGN SITUATION.
For example, in a more action-based multiplayer game where you can see the silhouette of other player's characters through solid objects to know where they are that is a situation appropriate for the silhouette argument. I'm thinking of the likes of Team Fortress 2 or Overwatch. I think in those games it's only the silhouette you have to know what character you're seeing through the object, therefore for the player to understand the situation they're seeing and to make the decision to go in or fall back they must be able to tell what characters/classes are involved from a quick glance. This is where silhouette becomes important, every character should have a unique silhouette. It goes beyond just having the character look good and distinct, there is an additional gameplay value to the silhouette being unique.
However, Pokemon is a turn-based game where once you engage in a battle (whether Wild or against a Trainer) you always know the current opponent you're facing. Therefore, the silhouette is not as important, the only time a silhouette may be used is with a Wild Battle to build-up some excitement about what Pokemon you're encountering. Because of this, SILHOUTTES ARE NOT IMPORTANT IN POKEMON. GF aren't designing every Pokemon thinking "if someone see this Pokemon as a silhouette would they be able to tell them apart?". With some Pokemon they probably do like the Starters and Legendary, but even then the design focus is more on the actual body shape and details rather then conforming the Pokemon to a certain silhouette. Pokemon wants you to see a Pokemon's detail and colors, because that's the part of the Pokemon which is most recognizable (likely because from that you can then guess Typing and possible Abilities & Moves; a silhouette of a Pokemon ain't good for that).
So going back to the discussion in hand, who cares if Eeveelutions after Gen II don't have drastically different silhouettes. The question should be whether the Eeveelution's designs get across what Type it's supposed to be.
- Vaporeon turns blue, ears/mane turn into fins, & tail becomes a fish tail; it's now an aquatic creature so Water-type.
- Jolteon turns yellow & ears/mane/fur all over its body becomes spiky; looks like it was just struck by lightning so Electric-type.
- Flareon's body fur turns red while its mane/hair tuft/tail turns yellow and becomes more puffy; it looks like it's formed of fire so Fire-type.
- Espeon turns lavender, a round jewel appears on its forehead, eyes glow, & tail has forked; sadly the symbiology of the tail is lost of most western viewers but the glowing eyes and forehead jewel may bring to mind mystics or fortunetellers so alludes to supernatural abilities, so Psychic-type since it's no dead thus can't be Ghost-type.
- Umbreon turns black, has red eyes, & glowing yellow rings which brings to mind the moon; it's a creature you don't want encountering in the darkness so Dark-type.
- Leafeon's body turns yellow but it's tail/tips of ears/hair tuft take on a green leafy appearance & has green leafy fur sprouts appear on its chest and legs; its a planimal now so Grass-type.
- Sylveon turns pink, eyes turn light-blue and bug-like light, ears become more roundish, & gains bows and ribbons; it's very feminine with a touch of insect that then could bring to mind modern day depiction of fairies which are small woman with insect wings so Fairy-type.
So, what about Glaceon? Well it turns cyan/light blue which that alone could bring to mind the Ice-type. However after that you do sort of need to read inbetween the lines to confirm that suspicion. It doesn't have Ice on its body, rather its hair tuft turns rigid & blue growing too long bangs. In addition the ears and tip of its tail becomes more angular and uses the same darker color blue, a blue that also colors its feet and diamonds on its back. It's not your typical depiction of ice which is, well, ice but rather a vague notion of ice crystals. The reason for this is likely because, despite the ice crystal depiction, Glaceon is more associated with snow than hard ice. They probably designed it with the thought in mind that it hunts and hides in snow so this would be natural camouflage with additional design details to make it more visually appealing hence the hairdo. Glaceon certainly isn't winning the award for best Eeveelution design but I do think it does represent its Typing. I mean, you say Glaceon doesn't look like an Ice-type so does that mean you also think Dewgong, Jynx family, Lapras, Articuno, Swinub, Sneasel family, Delibird, Spheal family, & Arctovish also don't look like Ice-types?