I agree. Bit of a gimmick if you ask me. I don't like scissor jacks due to their instability on anything but a perfectly level surface, but for probably the same money, you'll get a decent small trolley jack which would be a far safer bet, and far more useful.
A trolley jack is quick, easy and stable to use, and I always carry one in the boot/rear footwell of the car when towing. Best buy you'll ever make. That's why the breakdown services use them.
I hasten to add, although you probably know it already, that you should NEVER go under any vehicle supported solely by any kind of jack. Always use proper axle stands, blocks or chocks etc to ensure that the vehicle cannot possibly move, especially on places like the hard shoulder of a motorway where gusts from passing large lorries can be extremely dangerous.