EQ+ could allow the user to select and change multiple band at once. This is a use case typical of mastering.
What problem(s) would this feature resolve?
During mastering, it is common that the engineer needs to change the behavior of a series of band together. To the best of my knowledge this is not possible in EQ+ at the moment, and the engineer needs to change them one by one.
How does this feature fit in Bitwig as a product?
It would be just a natural improvement to EQ+ when used for mastering.
Is there already an alternative way to achieve this on Bitwig?
No to the best of my knowledge.
Could it be implemented using Bitwig components or APIs, without Bitwig team’s support?
No to the best of my knowledge.
Could it be provided by a VST or something else reasonably integrated with Bitwig?
Yes, Fabfilter Pro-Q 3 does it.
Are there other products that offer this feature?
Yes, see above.