I've never seen a workstation quite as easy to work with inside.
For starters it would be easier to simply push new hard drives into their bay until a locking mechanism holds them properly in place. Standard in other towers (especially in the workstation sector) since about 10 years or more. Heck - even in el-cheapo NAS housings they have such systems by now!
Instead with Apple you have to fiddle with retractable sleds and screws that are just ridiculously poor in terms of build quality.
Another example is the fiddly locking mechanism for PCIe expansion cards. And you always unlock all cards instead of having dedicated locking mechanisms for each card.
Don't get me wrong - the MacPro is a really well done machine - but it's not perfect and other manufacturers also have good ideas implemented in their offers!
But a radical redesign makes no sense at all. It should always be a tower, it should always have The Grid, and the positions of ports and such will and should remain basically the same.
Why should it always be a tower? If apple could manage to keep the thermal design as efficient with a smaller machine, it would not only save space on user side, but also material on Apple's side. And if a tower works best, does it really have to be as big as the current one?
Ironically with the tower being as huge as it currently is, it usually is placed on the floor. And in that situation the position of the front ports is sub-optimal at best. Even consumer-grade towers offer better solutions with ports positioned higher and/or at the top of the machine.
With SSD becoming increasingly standard in the market, the 2.5" form factor will also receive increased importance. Therefore I would not be surprised if some (if not all) internal drive bays will move to 2.5". Two 5.25" bays is too much in today's markets and the space of at least one of them could be used better with four 2.5" bays. And the 3.5" bays should at least offer the option of being used with 2.5" drives alternatively.
Again - it's a nice tower and well built, but it definitely has quite some potential for improvement!
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It's not ideal. It's more effort for developers, introduces some fragmentation, and limits the direction they can go with it in the future regarding screen size.
That implies that a developer needs/wants to make use of that extra screen real estate directly with his/her program. What if Apple thinks of putting that space to some use by e.g. showing dedicated information there (e.g. QuickStart bar or notifications or weather etc.) while a program is running?
Perhaps that space is available to developers as some kind of a dedicated utility screen of a defined size, where the user can (but does not need to) move controls or status informations from either iOS itself or one of the running programs?
With the iPhone hardware becoming increasingly powerful, multitasking today is less of an issue than during the introduction of the original iPhone five years ago...