The reason that so many fly fishing combo packages today contain quality gear is because manufacturers now are no longer "afraid" of bundling up items they only used to sell separately. In the bad days of fly fishing combos, the gear that was part of the combo package often was not sold separately. Instead, manufacturers often just invented a product line to put together as a package.
Now, the reason I bring this all up is so that people who have "been burned" by cheap fly fishing combo packages in the past won't automatically rule out buying a combo in the future.
But that was then and this is now. Today, while junky fly fishing combo packages still exist at Wal-Mart and similar big box stores, most combos that are sold from good retailers or at local fly shops contain a good quality graphite fly rod, a solidly made disc-drag fly reel and a decent (if not necessarily stellar) fly line with backing.
So, what are the benefits of buying a fly fishing combo instead of buying individual pieces separately? There are many benefits, actually. While most of the benefits are geared toward the new and beginner angler, even intermediate anglers will find many benefits to purchasing a combo package.