My wife and I started with Fins. They were great! Widely available, decent flavor, rechargeable and cheap to get into - I think the starter pack was $15. We didn't want to drop $100 on something that we weren't sure would work for us. The Fins worked and the rest is history so to speak.
So why did we "upgrade" to APVs and eGos and Clearomizers and such? Basically, while the cig-a-likes like the Fin or the Blu are cheap to get into, they are not cheap to maintain. The pre-filled cartomizers are expensive and sold as disposable; the small batteries won't get you through a full day and it doesn't take long till they aren't holding a charge well. Combine all this with the desire to try other juices other than "normal Fin" and "menthol Fin" and you have a pretty strong reason to start looking at alternatives.
The important thing, however, is that the need to look around a bit comes along at the right time. Vaping is needlessly complicated. For the new user coming in, all the talk of various devices, batteries, and threadings is very confusing. I remember the first time I started looking for upgrades, sitting there puffing on my Fin and being utterly lost by all the choices. The cig-a-likes work, are simple, and let you know if you might like vaping. My trusty, simple little Fins worked for me while I started to make sense of Clearomizers, Carto-Tanks, Bottom Feeders, eGos, APVs, and rebuildable drippers. By the time I ordered I kinda knew what I was doing. And I knew vaping was working for me; dropping that $100 at this point made sense because it was no longer a gamble.
The upgrades perform better, have a lower total cost of ownership, and offer more personal choice. But I don't hate the cig-a-likes, they have an important place in our little eco-system.