There pretty surely is such a niche, starting with people who are more comfortable with a designed database environment, or whose programming skills are more on mini-computer languages rather than the dozens of overlapping PC and web languages. I know I like the idea of simply designing a few tables and then linking them by keys and having apps flow easily from that foundation. If that gives me a web app at the same time (more or less) so much the better.
Even some PC-super-savvy programmers might find that helpful, they might like the nicety of a good RAD when they are working with an application with a number of linked tables. They may not want to invest a lot of time in tweaking their multi-code languages right and left.
Whether you like the Alpha environment (which does give you a lot of hefty integration to word processing, email, mail merge, data browsing and reports and such as a given) or not is really a personal preference, it is true that hiding the environment is not a good option, you don't have a tabula rasa. However in many cases that is an advantage, you don't reinvent many wheels in every program. Same with Filemaker.
My struggle the last time I used Alpha was that their Windows programming seemed to be more 'event-driven' where you would be telling what happens when this button or thingy got clicked, and those snippets of code did not seem to be correlated to an ease-of-use-and-see repository. Perhaps I missed something, that has been one of two reasons I am reluctant to go back to Alpha (although I may) remembering more fondly the Alpha 4 DOS days. The second was that they didn't always seem to be able to quickly, fully and decisively eliminate niggly annoyances, something mentioned above (or on the ProgHeaven page) vis a vis the browse mode. Not sure why that is, since it does seem to be a technically quite competent company. Despite those two concerns, every time they call me to do an upgrade, I am almost ready to say "let's go !".
Meanwhile I am earnestly considering WinDev/WebDev from France at the moment (partly because it interfaces to AS/400-Iseries data, my home base, partly because it seems to be a hefty and very competent and competitive product that has been active in Europe and worldwide yet a sleeper in the USA) although we are talking a higher price tag. On the even higher end, costlier, Magic Software from Israel, which used to win all the NC database RAD contests, is a very serious competitor and also very web-capable these days. Clarion is lagging in some ways but still is in the mix and has some pluses. All of these products, to varying degrees give you their environment (Clarion a bit less so, perhaps, it was more able to give you pure .exe files, a direction towards which WinDev is heading. Clarion was able to eliminate any concern about end-user pricing on an application you developed. However the product has not grown quickly into the 32-bit and web worlds like the others.) Another competitor on the high end is CA-Plex, that Computer Associates took over from Synon. And there are a few more. And each one will vary as to their ability to generate, integrate with and tweak lower-level code, written in C++ or other PC languages, and that will effect your decision. For one product it might be a non-issue, for another product this may be standard and a given.
WinDev and Magic allow you to download their actual product in a trial, limited version, so you can really see if it makes sense.
All of these seem heftier than the Alpha, Filemaker, Access level (amazingly the old-time goodie DataEase is still a viable product I learned the other day, so there are others.. eg Foxpro joined the Empire while Paradox went into a Borland space-time-warp-black-hole) and a person could easily decide to work with one simpler product and a heftier one as complementary, depending on the app complexity and specific needs. And still do the PhP and C++ and Python learning and training and developing as they move along.
Back on the simpler end, Alpha probably does have Filemaker beat on many rad-relational aspects, yet Filemaker also has its fine aspects and the Filemaker programmers seem to the 'work-around kings' nicely filling in the gaps this way and that. Access and its utilities probably lagging to those who like a full feature ease-of-use feature set.
Of course I have missed all sorts of other environments and products, folks who work in the Delphi and Visual Basics worlds, or those other products mentioned in the Jolt site, might have other excellent ways to achieve an ease-of-use full set. If others can share from diverse background, muy appreciado. Perhaps this discussion is well-placed here, maybe a different section, maybe Programmer's Heaven, maybe elsewhere ?