I think its more like having a huge number of copywriting jobs in the market without having a quality salary ...
The market is indeed growing but then there are more emerging copywriters who are willing to work cheap and hence the decline in quality and rates.
There is no decline in quality or rates unless you choose to associate yourself and compete with those lower-end writers. Those are the higher end tend to be doing just fine (and business -- and rates -- are still growing from what I've seen).
That's all well and good for the well established higher-end copywriters, but what about those who are still trying to get a foot on the ladder. Nobody's going to risk paying me £000's, when they can get someone established to do it. Conversely, who'll pay me £00's when someone's offering a service (which may not immediately appear inferior) for £00.00's? The glut of poor-quality "copywriters" has made the bottom few rungs a very hard place to be right now.
First, being new doesn't mean anyone should be at the "bottom few rungs" -- common misconception. If those buyers aren't you actual target market (and they're not if they're not paying what you feel your time is actually worth), then what they're paying poor quality writers is of no concern whatsoever (and those poor quality writers who drive their own rates to the ground deserve whatever they get frankly). Second, there's been quite an increase in advertised mid-range jobs with the poor economy in so many places. As an example, blogging rates advertised used to almost all be up to $5 per post. now we're seeing far more in the $10-25 range, and I've seen quite a few closer to $50 per post (check sites that post the job listings for you). There are even more new jobs that aren't advertised for writers who bother to network and build their own visibility (which is where most of the high paying work comes from). It's cheaper for companies to hire freelancers than full-timers, and they've absolutely been taking advantage of that fact over the last year or so as they trim their own budgets. Resourceful freelancers tend to do quite well in recessions (and even grow their businesses). How long they've been in business doesn't change the fact that there are more buyers of freelance services. Here's a tip though: get yourself networked with more experienced freelancers. When we turn down work offers, we often refer work to other writers we know and trust (just one of several reasons networking is vital during recessions -- any time actually).
Yup these traits are rare to find these days. Among that you should also include good relationship with customers.