The Romantic period indeed had more extended musical forms. One must not forget that the romantic period was a reaction to the Classical Period in form and in structure. Mood, passion, and love were reflected in the music of Chopin, Liszt, Berlioz, and Brahms, to name a few. Chopin's Nocturnes for piano were inspired from the nocturnes of composer John Field. The Symphonic Poem appeared in the music of Franz Liszt and Richard Strauss.
But there is a lot of confusion when it comes to classifying music into specific genres. Just like the romatic period, there is the classical period. I find it rather amusing that when you go to a music store it seems that the entire western music section from the 1600's to the present is categorized as "classical" music. It is true that it would be difficult to put specific genres into specific categories, but I find it rather amusing to see Ravel who was an "Impressionistic" composer, be classified as a "romantic" composer. Composers are trying to explore new ways to make music. Composers have always tried to explore the rules of music and find ways to break them. Beethoven reacted to the early forms of classical music and brought forth a new passion. This led to the romantic period. This is evident as Beethoven can be categorized into three periods. When looking at his 32 piano sonatas, one can see the tribute to form and structure in his early sonatas. He even dedicated his first piano sonatas to Haydn a "Classical" composer. But in the later piano sonatas, Beethoven breaks away from the strong rigid form, and they become passionate, with storm and stress. Composers are trying to break the mold and go forward. To be classified as a classical/romatic composer to Ravel would have been an insult to him. Ravel wanted to explore new territories. To be classified as a "romantic" composer would have been an insult to his creativity and to his genius.