It's not necessary to do an End User profile if you've done market segmentation thoroughly enough.
You need an End User Profile at this stage because you're close to preparing a sales and marketing plan.
The End User Profile should feed into the plan.
There is likely to still be a lot of variety among your target end users, even after you've explored potential end users in your market segmentation.
You need an End user Profile because you need to start evaluating prospective end users in follow-on markets.