If you've actually played on the beta and/or raid tested, you'll understand why even using raid logs to determine a DPS tier list at this point is terrible.
Some of the raid testing occurred shortly after a beta reset, so most chars had some serious issues going in (such as lack of conduits acquired, no legendaries, etc). For example, half of my guild's chars have bugged out or non-functioning Covenant powers. Some characters had access to two covenant powers for some odd reason. Depending upon the class/spec/covenant, that's a drastic change in how your class functions. Furthermore, not all classes have conduits implemented on the beta, so you're playing with empty soulbinds while raiding/dungeoning with classes that have some functioning and damn strong conduits. This isn't even going into the whole numbers pass argument, which is true to some degree, but they have adjusted some numbers on a broad level.
My personal spin on things: I'm still hoping for some mechanical adjustments to some specs, as even if they might appear to be doing well on that DPS chart listing and assuming it's accurate (it's not)... some specs just feel like trash to play at worst, not fun or awkward at best. If you're part of the higher end raiding community or know some people from that community, while performance matters when it comes to class balancing, something that feels good and/or does utility or odd jobs in a PvE environment can actually matter a lot more. Keeping in mind things like a few Nathria bosses had non-DPS related jobs to do, this is where actual class balance comes in.
Class balance isn't necessarily about getting everyone as close to a similar performance in terms of pure DPS. This also doesn't mean every spec/build has to have the same potential. Even if this were possible, you'd still see this sort of DPS disparity in the logs because player skill and preference matter, as well as your job in the content. For example, my logs will likely never be 99-100 parses because I'm almost always the person on my raid team that'll do the utility/mechanic jobs where I have to stop or lower my DPS to ensure something gets done properly, allowing someone else to tunnel the boss and get their sexy parses. That's fine, I'm okay with that. Now, if you're a raid leader and you have to multitask during an encounter, you may tend to gravitate towards a class that doesn't have a high skill cap or involved rotation but stable DPS output so you can perform both roles. If you're a skilled player, you may gravitate towards a class/spec that has a high risk/reward when it comes to DPS out... and people who think they're skilled will try to copy this 'meta' and while some will succeed, others will fail and may actually perform better with a class/spec/talent loadout that "sims" or "conventional wisdom says..." is lowering in DPS potential. These are just a few of the myriad of factors that actually go into what class balance from a designer's perspective is all about.
If you got a brain-dead spec with no skill requirement destroying every other spec in every scenario from DPS to utility, you might have some grounds to be concerned. But having disparity between the potential DPS of specs/builds in itself is not a bad thing. Having specs that are more simplistic or more complex is not a bad thing. Not everyone has the same skills level nor the same skill set. Having a diverse set of options for players of all skills sets and skill amount/preference is the ideal place to be. Some players can pick up any spec and perform extremely well at it in any scenario, the vast majority of players can't (or think they can but cannot).
Players get stuck in the meta build/comp mentality when the majority of the time players fail to realize the people that created that meta did so to compliment their skill set and playstyle (and strategy sometimes), and this tends to get warped into a class balance mentality. Even higher end mythic raid guilds still fall victim to this, sometimes struggling on content because they're obsessed with the meta versus tailoring their strategy or using a class/spec comp that works for their team (you try telling your officer team that you don't need 10 immunities on mythic N'zoth prog, it's not a fun conversation even though it ultimately was better than forcing some of our team players to play specs/classes they sucked at ).
Anyways, I digress. Point is this: there will be more class balancing in the future, and the end result won't be everyone has the same DPS potential on every spec, nor should it be.