Cisco Firewall :: 3750 - VLAN 200 Next Hop For Local Networks

Lets say I have the following topology.
 
DataCenter<---Etherchannel(2)-->BuildingB<---Etherchannel(2)--->BuildingA
 
There arer 3 stacks of 3750 at each building. The core switch/router in our network is at location B. The way it was originally setupis every L3 device has an ip address for each lan. So let's say we have VLAN 200 withnetwork 192.168.200.0/24. The DataCenter would be assigned (192.168.200.3), Building B would be assigned (192.168.200.1), and Building A would be assigned (192.168.200.2). I'm configuring the DC and BA to be L2 only and Building B to be the only real router in the network besides a few ASAs. When I ran a 'no ip address' on the vlan interface on Building A, the internet connectivity for 192.168.200.0 dies, but local connectivity is fine. After doing some research and troubleshooting, I found out that if I set the next hop on the ASA for the local networks for an IP address on building B everything works perfectly.
 
The way the routes on the ASA are setup for local networks are as follows.

All local networks have ip route localnetwork mask x.110.215.17. This address is the IP address of the inside interface on the ASA. Now, when I kill the IP address on the vlan interface on Building A internet connectivity goes down, while the next hop is still pointed to this address, BUT if I give it a next hop of the vlan interface ip address on B everything works fine. Now, I can easily fix this, I was just wondering why this is happening?