Trust me - it’s not that simple and straight forward as it may seem.
Even a relatively simple request (at first glance) can take tons of time & effort - not just in terms of development but also the overall legislation, compliance, internal processing, etc. Meanwhile, we also have to keep the best balance between our current daily tasks, already planned features, and prioritizing the new suggestions. Otherwise, we won’t be able to catch up with the expected quality. 
The point is: LISA, SIPP & JISA are precisely in the directions towards which we’re focused. We know that this is important for you, and we’re committed to delivering nothing less than outstanding service.