Helped with it's technical edge against its competition. I doubt it would have cost that much more tbh.
A technical superiority is meaningless if developers ignored it, and additional cost is a serious concern when the system is already considered expensive. Also, had it been included and widely supported, they would've pissed off everyone with a briefcase.
They didn't include it because they didn't think they needed it to compete on a technical level. They were right.
To a degree I guess. The MegaDrive & SNES still outlived it in the mainstream.
It's all relative. The PC Engine was catering to a different market, since Nintendo had a stranglehold on the mass market that was independent of software or hardware. Yet it went strong for 8 years and amassed a library similar in size to the Sega Genesis.
The Super Famicom/SNES arrived midway through the generation and only went s long as it did because of Nintendo's refusal to remain current hardware-wise and the combo of questionable business practices and japanese publisher "honor" and install base loyalty. Yet its last game was released during its 8th year.
While the PC Engine still saw releases in its 9th and 10th years, even one in its 12th and the first in a steady stream of physically published hombrew releases only a few years after that. And that's with the PC-FX targeting the same publishers and consumers.
No disrespect to homebrew releases, but I'm only including officially licensed software. By that logic the Genesis and SNES are still alive, as they get homebrew-esque stuff too.
I'm also not attacking the PCE or its achievements in anyway. It's an amazing little machine with some impressive punch. The fact it could output 482 onscreen colours at the same time when mainstream PC videocards of the time could only do 256, and cost a small fortune is pretty mind blowing.
I'm a HUGE Megadrive fan, but have to admit the graphics are sometimes lacking in terms of colour. Then again, not many devs took advantage of the MD's built-in 192 colour shadow & highlight feature. The highest recorded amount of colours of any game or beta from back in the day that I know of is 114, on a Sonic 2 beta. But yeah, I'm just rambling now.