They write excellent songs. They do have a lot of solos (like ToT) but they have produced masterpieces compared to PoS' song.
No it's not, since it's a matter of opinion.
So basically what you're saying is that you know nothing about music theory but you're willing to bet that there is an idea of objective, universal 'goodness' in songwriting not in the least bit subjective and that 'it starts' with music theory, which you know nothing about.
From everyone I know who knows something about music theory that is the case.
Subjectivity dictates if someone likes the music, not if it is good.
No, it really isn't. You can value guitar soloing very highly and think that it makes for great songwriting, or you can value disjointed compositions, etc. It may not be the norm, but there is no universal quality of 'goodness' in songwriting.
Who is to say what is valuable in terms of good songwriting? I think that is subjective.
I can hardly see how, DTs songs are nothing more than vehicles for solos.
I really don't see how you can sit there and simply say that Dream Theater songs are just vehicles for solos. Scenes From A Memory is pretty fucking exquisite, musically.