Quite so! After my old 'Vodafone Mobile Connect' card with its useless flip up antenna, I changed to a USB dongle. Software clashes were frequent and it never really lived up to its promise. At the time there were fewer hotspots about and the idea was that it would allow me to e-mail when out of WiFi cover. If it ever did work, it was expensive and erratic and it was a real pain trying to get it to use the correct network when abroad.
Whereas the MiFi device works a treat as the computer just sees it as being another hotspot. The only real issue is slow data rate in most parts of the country as anything other than 2G is still very patchy in many rural areas, no matter what the mobile operators might say. So it's really only of any use for e-mails rather than web surfing.
Typical use is in hotels whose wretched hotspots block e-mails - a very useful standby device.