There is kind of a weird difference in scale preferences, depending on where one lives in the world. In Europe and Japan, 1/72 still tends to be king since many households I think have smaller spaces to work with and display in (Japan for instance has very small living spaces for most people). In North America it is a little different. Here, 1/48 scale has the preference since many American households and apartments tend to be bigger. Hence, we have more room to stick the big kits.
When FineMolds first issued their 1/72 offerings, we knew they were intended for the Japanese market. The subjects were perfectly sized for most incomes and display requirements. Plus they engineered them in such a way for kids to build them. Later on though, I think they were getting some American influence since although FM's license is for the Japanese market, I'm sure they looked at the sales numbers to exporters like Hobby Link Japan and knew where a large percentage of their kits were going. At that time, the subjects began to get bigger (Slave One, the Falcon and the 1/48 X-Wing).
With the 1/144 Falcon, I see FM sort of getting back to their roots of the smaller subject for modest budgets. Of course they are continuing with the 1/48 line by issuing the Snowspeeder. Indeed I would love them to continue the 1/72 offerings as well since they have built up a very nice catalog and I would love to see it continue.
As for a 1/48 TIE, FM I don't think needs to go down that road. AMT's TIE Fighter 2 set I rank right up there among the best SW kits in terms of detailing and accuracy. And yes, combine it with an Estes Vader's TIE rocket and you can do the TIE Advanced rather easily. Combine it with the wings from an MPC TIE Interceptor and you have a decent model of that subject. Right now I have a TIE M-1 Experimental "TIE Bizzarro" in the works from the X-Wing Alliance game (TIE with one solar panel and two pods outboard of it, one containing a turbo laser cannon). If anything, the AMT kit is perfect for this conversion with two complete kits in one box and it can be done for much less then what a pair of FM TIEs sell for. All one needs to scrounge parts for is the turbo laser cannon.