SSAS: What changes would you like to see?

Kevin posted an interesting comment to my last post about how to setup HTTP authentication on Windows Vista and that was that this sort of thing should be built into SSAS itself. While this is not a bad idea, I don't know if it would be high on the list of things that I would like to see added to SSAS.

I don't have a written list as such, but here are few things off the top of my head that I would like to see in future versions. After I compiled this list I searched the connect site and added links to any related issues that I found. I encourage you to vote for any of the issues that you would like to see addressed. As Jamie Thomson has noted, the product teams do pay attention to the issues logged on the connect site. (So I should probably log my other suggestions on there too)

Here's the list:

A better way of dealing with calculations when there are sets in the WHERE clause.

Connect: Make MDX calc work with sets

Sub-Selects should set context in the same way that the WHERE clause does. I know there were reasons for making this behaviour different, but these two filtering techniques are being used interchangeably and some calculations work differently. You should be able to write a calculation and have it work regardless of the structure of a given query.

Connect: Subcubes should set current context
Connect: Sub-selects and the EXISTING operator
Connect: CurrentTuple property

Improved performance of parent-child and ragged hierarchies.
Aggregations over parent-child hierarchies. I have written ETL routines to "unroll" parent-child hierarchies in order to be able get a leveled hierarchy that we could build aggregations over. SSAS should be able to do this internally, even if it means marking the parent-child as "rigid" or something like that.
The ability to mix parent-child attributes in with other attributes in a single hierarchy. This would facilitate things like putting Country and State attributes over the top of an Employee hierarchy.
The ability to write "true" stored procedures that return a cellset so that you could either write parameterized queries for reporting or even use them in the FROM clause of a query.
The ability to cater for other authentication mechanisms. Maybe even by supporting a .Net interface for authentication, so that you could authenticate against a database, an LDAP directory or some other source.