Your opinion it seems quite reasonable and rationale, and must be respected, since a "little" version of GSM integrated into OPL could give us at least the initial benefit of de-interlaced and VGA gaming.
For instance, automatically enforcing to the proper progressive mode automatically, given the PS2 console and title region used (HDTV 480p for NTSC and HDTV 576i for PAL), by using the console region information hard-coded inside PS2 BIOS and hooking the SetGsCrt routine (where tipically the video modes are requested by the titles). Or enforcing to the VGA 640p or 640i for those using monitors (SoG via simple VGA cable or non-SoG via VGA cable with some circuit / modded PS2 output using the methods explained here and mainly those attached and shared into the first posts of GSM thread). But this latter option mentionated (the VGA one) cannot be automatically done, since it's impossible for the PS2 console recognizes that it is connected to a VGA monitor.
This integration with OPL could be done for all titles or per title (the last one seems to be better).