Some VST's are very well integrated into the host system. For example... The Native Instruments B4 running in both the Wersi and Lionstracs is so simple all you do is press the Organ button and choose the presets you want to play. There's no difference from any other arranger except the sound its producing is far superior.

Other VST's aren't as easy to use because they've not yet been integrated directly for the host. Still its by no means difficult to use and the sound advantages are quite significant.

Using an Open Ended keyboard is different from the likes of the Tyros, GEM, Roland, etc. Systems like the Wersi and Lionstracs offer so many features that if one chooses it can be as simple or as deep as they require. It all depends on the end user.

What's holding most people back from buying these types of systems isn't the complexity, its the cost. Yes, they do cost more initially but in the long run it will cost you less. Think about it, in a year or two you simply load in new software and have a new instrument, you don't have to sell your outdated keyboard for the next new model.