If you have every built a custom home then you know exactly what I am talking about. Most contractors are more than happy to provide you with a lighting solution. They do have a lot of experience in building custom homes so why not just let them decide where to put the lights?
I would consider a few things in making this decision. Do you want a custom home where everything feels perfect? Do you have a refined eye and will you actually notice the difference? Do you want the best layout for functionality? And finally, are you willing to pay out the cash to make the difference? If you answer yes to a few of these questions then I would suggest spending a few moments talking to a lighting designer about you house. They will often meet for a free consultation to give you an idea of what they can do and how they can provide you with the most value. They will talk to you about your needs and then provide high level solutions that they would pay attention to.
Having done a custom home I would say the design was definitely worth it. When I walk around my home I love the feel and attribute a large portion of that to a good lighting design. Although I think it is worth it for myself I might not recommend it for everyone. If you have to pay thousands extra for a good design is it really worth it? For me the answer is definitely yes. But for others it might not be. It’s all about how you see value and if you see the polish of a Lighting Design as providing enough value to justify the cost.
In short, I think it never hurts to get an opinion and realize what your options are. It only takes a few minutes to get a lot of good information about things you should consider. Even if you don’t go with the lighting designer for you landscape lighting or interior lighting you can still take the ideas and implement some of them on your own.