A "class" is a subset of mutually exclusive skills that define a playstyle.
In order for the idea of "multiclassing" to make sense, there needs to be a sense of there being multiple classes. For example, why do we say that Templar and Warden are separate classes? The shortest answer is that we would normally never be able to use abilities from both at the same time. Note that the "Class" (capitalized) we pick is an internal value each of our characters have which determines things like which Class abilities we have, but the general concept of a "class" (lowercase) depends on which mutually exclusive skills define a playstyle.
As mentioned before, a class needs mutually exclusive skills. With this logic, we can say that the Two Handed skill line is a separate class from the Dual Wield skill line. Both of those skill lines are mutually exclusive from one another, but you can switch between them via bar swapping. The "class identity" of Two Handed and Dual Wield in this example is diminished by the fact that you don't even need to run Weapon abilities on either bar, but it's not completely destroyed as you can never use Weapon abilities for the wrong weapon type on your current bar. A Two Handed bar will never use Dual Wield skills, and vice versa — those are two separate classes, just as a Templar will never use Warden skills.
This brings me to the main point of the post: Werewolf is, by far, the best class in the game.
You cannot use Werewolf abilities while not transformed, and you cannot use non-Werewolf abilities while transformed. It is the most locked-down playstyle, but its limitations and visual consistency make it the most engaging class by a large margin.
While Class abilities are no longer mutually exclusive (i.e., you can now use Templar and Warden abilities together) you cannot ever use them in Werewolf form. In order for someone to use Werewolf abilities, they must give up all of their other abilities — essentially swapping their "class" (subset of mutually exclusive skills that define a playstyle) to Werewolf. Note that their Class (internal variable that each character has) remains the same, as do their combination of Subclassed skill lines — what matters here is not their passives, but how their playstyle changes. A person transformed into a Werewolf will always use Werewolf abilities. It's not like how you're given the option to not use Weapon abilities for a Weapon-based playstyle; you must use Werewolf abilities if you're transformed, and you'll never be able to use Werewolf abilities when not transformed.
So, if you're feeling disappointed that build diversity is gone, or if you're looking for a playstyle with interesting limitations to build around now that Subclassing has demolished the barriers between Classes, I implore you to give Werewolf a try. Please actually take it seriously — it will never be the meta for PvE or for PvP, and it's got arguably even more limitations than Pureclass builds do, but there is still a meta specifically for werewolves! Yes, werewolves play differently from every other playstyle because it still has mutually exclusive abilities! No one will blame you for working with what you have; as a Werewolf, you cannot use the current meta abilities everyone else is using.
Don't like Subclassing? No problem — Werewolf plays the same whether you Subclass or not. If you did want to Subclass, all you need to spend Skill Points on are very few Class passives; it's the cheapest way to benefit from Subclassing. If you did want to play a Pureclass Werewolf, I'd recommend Templar Werewolf for damage dealing and Sorcerer Werewolf for a general PvP build. Of course, that is until something changes the meta again, like the third Class Set or a Werewolf Grimoire with support for Class Mastery. Maybe if Pureclass builds get a buff for keeping all three original Class lines, it'll carry over into Werewolf form, giving you more build options.
I personally really enjoy this playstyle — despite it being far from the meta — and reading all of the complaints about the death of build diversity gave me the idea to pitch the Werewolf playstyle to the community. It would also really help if more people played Werewolf — maybe ZOS would take notice and give it more quality of life features that everybody else has, like sneaking, Scribing, and appearance customization. Huge respect goes out to those of you who continue to play Werewolf despite it being an inferior playstyle to whatever the meta has become in this post-Subclassing environment.
PC/NA — Lone Werewolf, the EP Templar Khajiit Werewolf
Werewolf Should be Allowed to Sneak
Please give us Werewolf
Skill Styles (for customizing our fur color),
Grimoires/Scribing skills (to fill in the holes in our builds), and
Companions (to transform with).