*finds it amusing that people who never ever brows the forum subcategories and always use new and active posts always complain the most about the subforums they self-admittedly don't use -- save when making a thread of course

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As for the forum structure, its there to provide a clear display of the sites content to new and existing users. A single menu structure can work, but only with a very very small population (ie the typical population you'd get on most average flickr groups, where there is only one single list of content). When you have a larger population you have to segment the content, otherwise you'd all be complaining that posts fell of page 1 too fast - then we'd extend it till the single page was showing a long list of posts (say 50-100) and then you'd all be complaining that you can't find anything specific because its all a big jumble.
And that is just for existing members - for new members it would similarly be a very messy interface to view and very hard for them to get an idea of the sites features and overall content.
In addition you can search the site based on limited segments - finding info on, lets say, specific camera models is much easier when you can limit the search to only the tech subsection and thus get results more in line with what you're after, rather than pulling up every single thread where a camera model is mentioned (which would likely pull up loads of photo threads with no tech details and the like).