In the MyWi description on Cydia it says "Create Wifi Hotspot to connect multiple laptops or mobile devices to share your iPhone's internet connection"
I've personally connected two laptops with MyWi.
As for others not wanting to jailbreak,
Some like the ability to update to the latest firmware when it is released.
Some are very happy with the iPhone in its stock form, so why would they jailbreak.
Its all just personal preference.
i think i have connected ipad and my laptop at the same time with MyWi too