Equipment swaps are CRITICAL for druids, and carrying multiple sets of gear is absolutely worth the bag space.
At your level no matter what spec you are you should absolutely carry a feral/melee set with agility, strength, and stamina, and another casting/healing set with intellect. When you hit late 50s and especially Outlands, you'll find gear with +healing and +spell damage, too, which is great for casting/healing set. If you're feral you'll also see gear that's differntiated enough to merit carrying THREE sets: casting/healing, dps for cat form (strength and agility) and tanking for bear form (armor, stamina).
I personally recommend that people focus on building up whatever supports your spec, but still look for AH bargains on off-spec gear. You'll collect some greens along the way that support your off-spec needs, too. Rolling "need" in instances on off-spec gear is dependent on the group and situation, some groups won't mind others will.
Macros shmacros, though. Get one of the two popular addons Outfitter of ItemRack. They can both automatically swap your gear when you shift forms.