When you say you want to allow a customer to modify an order that has attributes....do you mean you want them to be able to edit their cart contents prior to checkout, or you want them to be able to edit an order after it has been placed and paid for?

RE: editing cart contents - I use Edit Cart and find it very easy. I'm not sure what you mean when you say it's not an easy customer focused solution. When a customer loads a product with attributes into their cart, and then changes their mind about what they want, they have only to click an edit link to return to the product page and change their selection. This is much easier than in a physical store where they have to wander back up and down the aisles putting things back and selecting new items :)

RE: editing orders - once an order is placed, customers have no access to it (only to a record of that order which is available in their account). Allowing a customer to access and edit an order would be akin to allowing a customer to come behind the counter in your physical store and process their own return or exchange.

There IS a mod that will allow the store owner to edit the order at the customer's request (and also of the owners own volition for administrative purposes). It is called Edit Orders and it's very cool (and does a WHOLE LOT MORE than what you're looking for) - but it DOES have it's limitations in terms of editing product attributes. If you're interested in editing product orders with product attributes in the admin, best to visit the Edit Orders support thread, make a post about what specific attribute edit function you need, and ask if Edit Orders will do that.

Beyond the attribute editing limitation however, it's a very cool mod that is currently undergoing updates for ZC150 - the current stable release works with ZC139. It is one of those addons that almost every shop owner needs but doesn't know they need it until they go looking for the functionality it provides. And while you're at it, check out Super Orders, which has different functionality than Edit Orders, but they are designed to work together.

Hope this helps :)