I'm a big fan of David Airey's site and design blog. He just recently posted a blog about a logo design request he received, similar to other job requests he receives from time to time. This request had the potential client telling David exactly what they want their logo to look like, and that they essentially just need a designer to execute their design.
The point of hiring a designer to help create and develop your company's logo is to utilize someone's creative talents and experience (a skilled designer) to work with you and offer a design that is better than anything you could have come up with on your own. If you already know what you want why would you pay someone else a bunch of money to execute the design?
Leave the creative heavy lifting to the experts. A good designer will want your input and will listen to your thoughts and concerns. From there it will be apparent that the designer understood what you wanted and pushed your vision further than you could have on your own.
That's why you hire a designer, or a writer, or someone to help you build a strategy, because they have talent and experience and a creative approach that can elevate your initial thought of what could be in these realms. Otherwise, you're really just looking for someone to simply execute your own ideas, which is totally fine, but if you're not really an experienced designer, writer or marketer the end result may be less than it could be.
I will say that I am a proponent of empowering solopreneurs and small businesses with tips, tools and advice to help them discover and/or create their own marketing materials as a result of their small budget and need for cost-effective solutions. This usually becomes a learning tool for the small business - they learn enough to be dangerous and get what they need done for the time being (and some actually find that they have some talent in these areas, which is great), but most do what they need to for their businesses current start-up necessities and move toward hiring a professional as they build their company beyond those beginning stages that required such tight reigns on various costs.
The result is they learn a bit about what goes into the design, writing and marketing strategy-building process and they gladly hire an experienced brand communications specialist to do the heavy lifting with a better understanding of what they're paying for.