Well, my two cents:
1) Inclusion of copyrighted material. PPL don't want to dump their roms, don't want to use C-BIOS and don't want to surf on torrents to find out ready to use machines. They want a combo box to select: Plain MSX1, MSX1 Japanese with DD, Fully Loaded Turbo R with SCC, Moonsound and GFX9000, Perfect Game Configuration (2+), SymBOS Configuration with included HardFile, etc...Well, my two cents:
1) Inclusion of copyrighted material. PPL don't want to dump their roms, don't want to use C-BIOS and don't want to surf on torrents to find out ready to use machines. They want a combo box to select: Plain MSX1, MSX1 Japanese with DD, Fully Loaded Turbo R with SCC, Moonsound and GFX9000, Perfect Game Configuration (2+), SymBOS Configuration with included HardFile, etc... Panasonic, National, Sony, etc...... copyrighted ROMS must be included.
2) An integrated GUI.
OpenMSX have so many features, but you need to be an expert to tweak it and configure it as needed. OSD menus are great for Mobile versions (where are they anyway?) and Catapult is not user friendly.
Something similar to BlueMSX GUI should be enough.
3) HAP could help them to include PSG Factory and those GFX/Tile viewer/editor from Meisei. Those are really nice additions.
*PS* I'm not judging if my suggestions are legal or not (period).