This may represent a big change to the technology, I don't know. But it would be quite helpful and would expand the power of the platform if we could apply indicators to other indicators. Typical examples of things I'd like to do is apply a moving average, standard deviation, or linear regression to the series of another indicator. As it stands right now, in order to do any of these things, we have to get into custom programming.
The idea is good, although not new, since Tradestation can do this natively since years already. However, neither MT4 nor MT5 can do that, the indicators always need to be applied to a time series, which is the data of your price chart. Hence the SQ team would need to recode every indicator from scratch and come up with completely new functions to support this in MT4 and MT5, and even then, the language is so limited that this will not be possible for every indicator. If you ask me, it´s pretty much impossible to do apart from Tradestation code.