Some of your question is about music theory, but I sense it's more about composition and comparing acoustic instruments with the DAW.
I can never manage really emotional songs
If you are still learning the composition or performance skills for creating emotional music, and you input in the DAW with the mouse, I think the DAW will get in the way. Physical performance - either with an acoustic instrument or in real time with a midi controller - will give the immediate feedback needed for the learning process.
harbour creativity and a better understanding of more complex music theory
In some cases the DAW might aid with this learning. For example, you can cut and paste, transpose sections, re-order sections, change instruments, and do other manipulations quickly and then hear the results right away. Those things are more about the composition process. For learning theory I feel it's best learned by looking at actual repertoire and learning how theory is applied in actual musical context. Developing some sight reading skills - even if the playing is sloppy and incomplete - is probably more useful for this learning than to input music in a DAW.
I struggle with the extra 'flares' that you can have on piano arrangements
This is where I think the DAW will really fail. If you don't understand piano technique, and sequence fast, flashy passages, there is a risk they will sound fake. Sure, it's possible to sequence realistic virtuosic piano music without knowing how to play the piano, but it's not likely.
I think you need to ask yourself how much you want to emulate "acoustic" music performance. If you want a really convincing imitation of living, breathing people playing acoustic instruments, you should spend some time learning to play them. Learn about their unique properties. Imagine sequencing a violin part with no awareness of the open strings or bowing technique! Learn about the instruments and then bring that knowledge back to the DAW.