I'm sorry, I modified modules/org/jboss/as/web/main/modules.xml and not modules/org/jboss/as/weld/main/modules.xml !
I finally modified the 2 modules.xml files as you describe in your workaround, and all gone OK (just that I was forced to copy the "main" and "1.2" directories from modules/system/layers/base to modules/ because the multi-JSF feature couldn't understand the new 7.2.0.Final modules structure.