The problem you are mentioning is generic rather universal. Every client wants to capitalize business from his site to the levels possible but not every client understands human psychology and rules of human interest and engagement. You cannot blame customers entirely for this thinking as their learning resource is real-world and in physical stores, the more on display you have, the more likely it is to sell. Customers carry forward this thinking to their web projects as well and expect more is more but this is why we, the designers learn and get our business from.
We sell our customers satisfaction, not from the designs alone but from the "service" we offer and guiding customers to the right strategy is essentially one of the part of this service. Now what can you do here when customer is refusing, well it is a subject vast enough that I can write two books on but in a nut-shell, you need to show him a part of your thinking process by educating him.
Now how can you educate a customer? hard job but there are no short-cuts, Either you deliver him what he wants and the way he wants or you offer him what is right and what his business needs - but he needs to understand that what you are suggesting is actually good for his business and he should listen to you more. You don't need to bring him equal to your level of understand on the subject but you need to EARN ENOUGH CREDIBILITY FOR SOME MATTERS in his/her eyes so he may start relying on your judgement for the other matters, even the matters which he doesn't know well. That is the start and that is the end to this problem.
You should have this discussion way before you show any of your designs to your client. Learn from him and when he tells you what he expects, this is the opportunity where you can correct some of his dimensions and understanding of digital world. If you don't make this ground and show your prepared stuff straight-away, you are most likely to receive same comments every time.
Hope this helps.