I think one of the major problems of "user-friendly" linux distributions/desktops nowadays is, that they try to make almost everything work automatically and without providing sufficient tweaking tools for the case where the automatic things fail. The usual argument being brought forward is that "my grandmom would be scared if I present her a 'Enter custom AT initialisation string:' entry field", the net result being that grandmom now has to search the web and download wvdial and the corresponding configuration file.
On the other side, the UMTS-USB-Dongle vendors (and network operators that sell those) aren't interesting in generic solutions that work out of the box with every compouter or operating system: Their products don't differ by (easily measureable) performance- or feature parameters and are distinguishable only by the added bling- and eyecandy the bundled windows-software provides.
I only used UMTS/GPRS internet connectivity a few times in the past, so my oppinion stated here is not based on any solid experience, but I know that it can work very well without much effort if a useful interface is chosen (a HTC smartphone provided a emulated ethernet card via USB to my Linux notebook). On the other hand with the currently sold popular UMTS-USB-dongles one has to jump through a lot of hoops just to disable the added bling the vendors try to impose on the Windows user and finally get to a useful modem-emulation port that, in the end, is handled by the well-proven infrastructures very well.
{e.g.: having to register the USB vids/pids with usb-serial instead of using the generic modem class, using special registers on the stick to disable the emulated driver-cdrom on the stick instead of using USB alternate settings, sending magic commands to enable the correctly working AT command interface instead of defaulting to, re-configuring GPRS APN, and finally dialling the magic *99-telephone number, or whatever it was, I forgot most of it already. The last item finally will work with any GUI friendly dialer, I'd say, but who cares about doing the first steps on the console?}
