I know there's XBTFreelancer and other sites like that but I like the forum format better.
Your subjective opinion doesn't make this a good idea, in fact, as it stands now your concept sounds terribly inefficient and very cost intensive.
I want to do this because of the state of the services section - it is too cluttered and unorganized.
The services section is quite cluttered indeed but replacing that with your forum alternative is only going to partially solve this issue. I'm assuming you're going to make a bunch of sub-fora for each specific job branch. Now this will make things a little bit more organized but still inferior compared to concepts like XBTFreelancer. Since those sites allow you to set specific tags for each gig. That way it's very easy for the freelancer to filter out the gigs that aren't in accordance with their skillset. You could even go as far allowing the freelancer to set default tags on their profile and notify them when a new gig, that fits their criteria, is posted onto the platform.
On your forum, on the other hand, freelancers will have to continuously browse the forum (or multiple subfora) for new jobs. Which for obvious reasons is extremely time inefficient.
I will mod it to include a reputation system like this forum have I haven't given such a modification much thought but I want to be able to flag scammers, lazy employees, and people who are unqualified to do the job.
I hope you realize this will either require a lot of work or cost a whole lot of money (given this gains traction in the first place). You could avoid unnecessary costs by leaving the majority of the work to the users. For example: After the gig is posted onto the platform freelancers have a certain timeframe to apply for the job. When the timeframe is over the creator of the gig can go through the applications and select a freelancer, based on rating or work history or whatever. This action creates a private environment where the freelancer can view the job details, the creator and the freelancer can interact with one another. The funds are held by the platform and can be released upon request by the creator of the gig (If the creator is not satisfied with the work he/she can open a dispute and the staff will review the case). At the end of the process, the creator of the gig can rate the performance of the freelancer and leave a review.
My questions are: would you use it and does it serve a good purpose?
It does serve a good purpose (you're trying to employ people) but if you're determined to stick with the whole forum idea it would be a definite
no for me.