The terms "will" and "shall" have an accepted meaning in UK law relating to obligation.
There's a separate issue here about how we define benefit. You haven't indicated what the planning application is for, but in the typical scenario of housing development, there are two sides to the argument. On the one hand, people talk about the loss of land, spoilt views, increased traffic, pressure on utilities and services etc. The alternative view is that new housing allows older children to remain in their community, provides affordable housing options, supports local amenities, creates and supports jobs, and brings hard cash in the form of S106 or CIL to invest in local infrastructure.
I live in a village that has died due to a lack of new housing. We've lost our two shops and a post office, two pubs, the village school and last year we closed the church. The village hall is our last remaining amenity. Residents still claim that the village is just the right size and shouldn't be allowed to expand, but it's five times the size it was 100 years ago and has grown steadily throughout that period.
Sustainable growth is essential.