Wrye Bash is completely indispensable for OB, and anyone wanting to use any kind of general overhaul as well as any other mods along side it HAS to have this tool. In case anyone doesn't know, the main reason for this (as the tool has other uses) is because instead of each field inside an id being able to be edited separately, all data for an id are taken from the last one loaded in the load order and changes made to the same id in a mod loaded earlier are all lost, even if its to a different data inside that id. Wrye Bash combines them... making it so if you edit the inventory of a character in one mod, you can also edit the level/stats of the same character in a mod loaded later, and get both changes. I would hope if they are rebuilding the engine from scratch, that this would certainly be the way it works stock, without a third party app.
OBSE allows more scripting capabilities and scripting sizes. I would hope that Bethesda has the foresight to make the script portion of this new engine be capable to exceed the limits they require of it as a stock game. If they expect people to mod, they should anticipate the need to allow it to grow beyond its out-of-the-box bounds.
Wrye Bash and OBMM both are able to maintain your load order much better than the launcher. Added stock capabilities for mod management shipped with the stock game would be fantastic.
In any case, its not really a big deal to USE these tools, and all mod users like me are spoiled that someone took the time to make them... but its a lot of dependency on a third party taking a huge amount of time and effort to make something work the way it should have worked in the beginning. It kind of is a big deal to expect someone to have to make tools as opposed to just making mods. I wonder how much work will need to be done this time around.