As fast as computer 'architectures' change, anyone thinks an 'open' system future-proofs them is a bit optimistic.

Let's just take the expansion slots as an example. In the last ten years, there have been FOUR new, totally incompatible slots for computers, from PCI through to PCI-e (or whatever is newest, I can't keep track of them all!). There have been three changes to USB. There have been innumerable chipset changes, and some significant differences between different CPU architectures.

These are where your soundcards go, where your storage peripherals and external controllers come into the system, where the raw computation of the entire machine resides. Not exactly 'future-proof' by any means...

Secondly, you have to take into consideration the enormous COST of developing the sounds, styles (especially the styles) and the OS of any of these arranger products. If the development costs are ONLY paid for by minor upgrade fees, that's a DRASTIC loss of revenue compared to what a manufacturer gets by selling you an entire NEW keyboard to go along with those styles and sounds and features. Now, you might THINK the closed arranger manufacturers are greedy bastards who are just out to rape you, but that money is NEEDED... I mean, just take a look at just how POOR all the included content is with open arrangers, how unintegrated and piecemeal it is, how it compares very poorly to a closed one. All that extra money that buying the closed arranger is going towards some VERY important 'software' features. Ones that, without that higher cost, are being short-changed on the open arranger.

There's both sides to this coin, all is NOT nirvana in open-land, and wishing that the same amount of work be done for you for a tiny fraction of the price is dreaming in the extreme.