That was my thinking too (see post 19), and I agree with you about the idea of a disk access mode for LR - it would be great for people who don't want the Lightroom Library approach, but do want the other features. I manage it by using the LR Library approach as is, then export the files to my own file structure, which I then manage in Bridge for all those images that will be further worked-up in PS. This combo works fine for me and is very easy to do.
LR and PS are not substitutes and they were never meant to be. There will always be a slew of things one can do with images in PS that simply fall beyond the scope and philosophy of LR. So it really isn't a question of expense, but of basic needs. Whoeever needs no more than LR, well they've saved themselves a few hundred bucks, but if you need more you pay more - "vat else is neu", eh?
I believe that the key thing here is to let go of what one is used to, and that is in essence "physical storage" one is so accustomed to (we are used to store things physically: on a shelf in a cupboard in a room in a place). Storing files on a disk in a directory structure is a 1:1 match with the physical storage we are used to.
Catalogs, like LR, are a layer on top of physical storage (a "physical" file has to be in a "physical" place on your harddrive(which is again physical)), that allows you to add logical concepts to the management of your files. For example one can make combinations of images to meet a particular purpose, without the need to alter the physical storage of the image files. Quite identical to a real life library (a public library with many many books), where one would rather go to the cataloging system first to find books matching certain criteria and where they are physically stored (room, cupboard, shelf), than to physically go through the storage of books, and physically read the titles on the backs, etc. In very large libraries one does not even have access to the physical storage anymore, but books/documents are issued upon request via the cataloging system.
In my working life, primarely physical-asset data management related, i once had a meeting with a librarian of a very large technical documents archive of a large petrochemical company. He made a study on how often it is needed to create a physical copy of a file(=document) to create a complete physical dossier(for a particular purpose like applying for a license to operate, environmental, etc) for a given master document (master doument referencing other master documents). It turned out, that on average each master document needed to be copied about 26 times.
For a library (or archive) of any size (this was a case of more than 3 million documents), increasing its physical size 26 times is monstruous and economically not very viable. Not to mention issues regarding the propagation of updates.
With a cataloging system, effectively on a computer that could fit in a locker where one keeps brooms etc, the same goal could be achieved (and was achieved), at much-much lest cost and time, and much less hassle in managing updates and their propagation.
Now coming back to catalogs like LR, obviously will not contain that many physical images. But the possibility any image will eventually be part of many collections (dossiers if you like) is as likely as in the above example(or perhaps more likely). Also: searching a particular image by filtering to bring the total number down to something that is overseeable and results in the right image found in an aceptable time-frame, or do a roundtrip to PS to modify the image while retaining the link to the originating image, or etc(fill in yourself, depending your way of working).
The digital era also added a few more options to create multiple versions or variants of the same originating image, options that in the "physical era" were limited, and if possbile costly, time-consuming, and usually with image quality degradation as a consequence.
So i really believe a catalog is needed, it is a "layer" on top of the physical storage, therefore has to be seen as two inseparable aspects of what in the end provides control over your invaluable set of images, for whatever purpose they are used for.