Usage of contacts instead of addresses

When installing the base_contact module, partner is organized like this:
1 partner can have one or more addresses and each address can have one or more contacts.

Unfortunately, all other forms of OpenERP don't use it. (I.e. CRM, Users, etc...)

So when installing base_contact we should be able to choose a contact of an address instead of an address. Which is not the case currently.

Concrete example:
- Company A - created as Partner A.
- Company located on two sites - created as two addresses (1 & 2) of Partner A.
- Three employees/users, one located on site 1 (created as a contact of address 1), two located on site 2 (created as two contacts of address 2).

When you create user 1, you can link it to address 1 --> So emails will be sent to the generic address of the company (<email address hidden>). And not to the email address of the contact (<email address hidden>).
When you create user 2 & 3 you can only select address 2... so only one email address for two users. Which is not correct neither.

Exactly the same behavior in CRM. When creating a case, you can only select an address as a contact. Which is not correct neither.