Yep, you see this all the time in the iOS development community too. People coding my sticking together 100 slightly incompatible 3rd party libraries, and writing a bunch of glue code. Then hitting problems and responding to help solving them with "we can't do that, we're required to do it this way because the 3rd party library does it that way".
Exactly. I don't mind including a good tool that does its job well and leaves everything else alone. But I've run across at least 2 very sad "syndromes" that add-ons sometimes cause:
The first syndrome is represented by libraries that take over everything and unnecessarily restrict your otherwise legitimate actions, because they ASSUME everything will be done with or through them. 2 great examples come to mind from the Ruby world: Formtastic, and Devise.
I dumped Formtastic because it insisted on generating its own <ul> for the form, and <li> tags for all the elements, which prevented you from laying out your forms your own way. Trying to wrap elements in named or classed <div>s so you could do your own layout resulted in invalid HTML. Maybe Formtastic has improved since then, I don't know. I discussed this problem with the author, and his response was "Why would you want to do that?" Which just illustrates my point.
Devise is way too intrusive and makes too many assumptions. Besides being based around unproven Bcrypt (which has never been fully security audited), it tries to force you to do everything else its way, too. It may be "customizable", but in my experience that's far more trouble than it's worth. My opinion is that most people who use Devise do so because they don't understand how to do it themselves.
The second syndrome is "copy and paste development". This irritates me to no end. "Why don't we just use X? It already does that." "Well, because it's like shooting an ant with a cannon. A cannon that also wants to wash your dishes."
The right tool for the right job. Often, especially for small jobs, it's vastly preferable to roll your own tools, and do it your way.