The E8/E11/Platinum 1000 series can all use the same patch loom, but the E6 ECU was built differently and sort of stood out on its own..
It's not that your ECU is 'old' per say, it's the entry level ECU in the previous Haltech series that will still suit a vast majority of setups out there. It's just that tuners have become accustomed to newer technology which gives them greater control in tuning with automated ECU mapping etc which equates to an easier and quicker tuning experience. The newer ECU's are jam packed with features to suit many applications too, but you end up paying for it, even if you only use 20% of what the ECU can actually do.
Whether its 'laziness' or being 'spoilt', tuners will work with whatever they feel most comfortable tuning with to obtain a better outcome in less time and headache. Technology does that lol!!!
It wasn't that long ago when most tuners were tuning the popular Haltech 'E' series ECU's and they were commonplace everywhere in a modified car. They still have their function where a newer ECU is not required, so it depends on what you want to run with the ECU. With newer ECU's comes newer advances in tuning technology where you can take advantage of things such as flexfuel monitoring and adjusting fuel maps on the fly. The newer ECU's obviously have the functionality of these processes programmed into them, whereas the older ECU hardware cannot support it (so flashing chips and boards wont work).