Is it worth it to write your own software (tools), if you don't care for what is currently available? (semi-rant)

I'm a developer, and I have an affinity for FOSS (free open source software). That said, there are a lot of useful tools available in the form of SaaS offerings ("cloud" based, runs on someone else's servers).

Some tools are great, like Remember The Milk, Twitter, Github, etc. But I always get that nagging feeling at the back of my head saying "don't trust what others could do with your data", and so for things like my calendar, bookmarks, etc., I host my own web apps (K5n's WebCalendar, Scuttle, etc.).

My question to reddit is this - if I have that nagging feeling about SaaS, should I bother to write my own tools to fill those gaps? Is it worth it to push forward and support the ideals of FOSS and creative commons compliant licensing, and to support and advocate personal privacy, or are those ideas (ideals?) now just whispers in the wind?

I've been a linux user for a very long time, and migrated away from Windows many years ago because if its proprietary nature. But it just seems now that the Internet itself has become this proprietary environment, with every SaaS provider attempting to lock you into their service and track your every move.

Do others feel the same way? Are there groups or projects focused on this problem? Is it a problem?

There is an interesting book that I came across (haven't read it yet) which seems to discuss similar ideas:

Nothing to Hide: The False Tradeoff between Privacy and Security ISBN-10: 0300172311

Anyone read this book?

Note: I'm posting this to r/technology to reach a wider audience. I could have posted to r/privacy, but I would expect the responses to be a bit biased. r/programming seemed more appropriate, but they don't allow text submissions.