Like everyone else here has said, there is nothing inherently wrong with laminate at all. Many sound fantastic, and they are considerably less expensive than solids.
But, a quality solid will simply sound and age better than a laminate, despite how good that laminate is. There are properties of solid wood in regards to vibration and resonance that laminates simply can't duplicate because laminates don't have uniform grain, structure, etc. Of course, the type of wood and the quality of construction are critical, but all things being equal, solid wood adds texture and character to the sound that laminates (by their nature) are incapable of.
It's like anything else where one can compare. A Honda Civic is a fine car, but it isn't a Lexus iS or an Infinity G35. A DVD is a great way to watch movies, but it isn't as good as a Blu-Ray. The old PS2 is a really cool gaming console, but it isn't as awesome as the PS3.
So, when people go on about solids, it isn't meant to imply that laminates suck, but that solids are (usually) just better.