That is exactly the way all the big box retailer want it. Its the right way too. If the anchor doesn't want the LL to build on the additional land, then they should pay additional rent while the land remains undeveloped.

normally the larger anchors want their parcel ID numbers in order to appeal their tax assessment. and the land onwer is often agreeable because they don't want the rest of their land depreciating if the anchor's property depreciates. that's actually one of the few things both sides will agree on.

the anchor will usually option additional acres for future expansion. the rent is obviously negotiated accordingly. another consideration is the convenant to open. is the anchor required to open for 6 months (the landlord's preference), or 1 day (the anchor's preference)? this can often kill the deal b/c anchors would normally never agree to a covenant to open for more than 1 day.