Is it a little odd that Republican is the same as a noun and an adjective while Democrat (n.) and Democratic (adj.) are different? Sure -- English is rife with such inconsistencies. Is it a little unfortunate that one party's adjective, when lowercased, has warmer and fuzzier connotations than the other's? Perhaps.
But . . . tough. That's the way it is. There was a time when the -icless adjective might have been read as an attempt at linguistic correction. Today, it is bound to be read as a show of solidarity with Republican propagandists. Use of the big-D word doesn't mean that the big-R people aren't interested in democracy, and use of the big-R word doesn't mean that the big-D people are enemies of our republic.