At first glance, it makes sense to use your phone to control a TV or cable box. You have it with you all the time. But that's actually a drawback. You have it with you all the time. If you share your home with others, they'd need to have smartphones capable of the same functionality as yours. Sure, your loving family can bust out the old school remote controls when you're not around, but an iPhone will never replace things that still have to be kept at the ready. Even if you're not leaving with the phone, there are still ways for it to be out of commission, forcing your family to return to the savagery of a regular remote control. Say you've been playing with your smartphone as many of us are apt to do, and you've run the battery down. If it's in need of a charge half the time, it's not practical to use a remote.
No one likes a remote-hog, and that's just what you'd be if your phone was the remote control. Let's face it, you aren't going to want to pass your expensive, shiny smartphone around the room for all to fumble with. Even if you do, these apps aren't going to be as intuitive to use as a real remote. There are likely to be people around that don't get how to work your fancy universal remote app.
The experience of getting your setup working with Phone apps is likely to be a rough one. The iPhone doesn't have an IR port like a real remote does. These apps rely on Wi-Fi to work, and most of your home theater components aren't Wi-Fi capable. However, companies like Samsung and Pioneer are beginning to put out Wi-Fi devices that can take advantage of iPhone apps; different apps. There aren't any real standards here, so we aren't really talking about a universal replacement. When you have to run completely different pieces of software for each component, it becomes less useful. There are devices like the NewKinetix or the RedEye mentioned in the earlier post that can act as a go-between turning your iPhone commands into IR, but you've just shelled out for another piece of pricey hardware.
Look at the way an iPhone handles apps, and you'll see another drawback. You get the apps through iTunes and they are tied to your account. If there are multiple iPhones to control the TV, you have to have those apps for each phone. If they aren't free that could get expensive. If you decide to switch to another mobile platform, the apps you've bought are worthless.
In contrast, a real universal remote has proven itself to be a viable option for most anyone. The more refined an elegant solutions like the Logitech Harmony remotes can even give you everything you need. The setup process is easy, there's no tediously typing in IR codes. Logitech provides Mac and PC-based software to handle this function. With an iPhone, there are only so many devices that will work with each app, and only so many that work with a Wi-Fi signal at all. With universal remotes like the Harmony, that isn't a worry. Even if Logitech doesn't have codes for your device (which is unlikely), many remotes have the ability to learn IR codes right from your old remote control. So even that weird off-brand TV you got five years ago can work with the remote. That's not likely to be the case with an iPhone.
Another big advantage of a physical remote control is that they just work, as the old adage goes. It's impractical to use a touchscreen to control your TV. Sure, it works, but real buttons are best for this. You're going to be looking at the TV, not your hands. It's surprisingly easy to miss while rapidly tapping at a touchscreen and not looking. A touchscreen is fine for occasional use, but flipping channels is going to be less aggravating with real buttons. There is something to be said for a dynamic display that can change based on the situation, but the iPhone isn't the only way to get that.
Most remotes in the Harmony series have an LCD display that can be used to program specific functions. This is called the "Activities" function. In all the ways the iPhone might be intuitive, it can't touch this. The Activities are basically macros that you can program. In order to watch a Blu-ray a number of things probably have to happen. The act of turning on the player, changing the picture setting, and switching TV inputs can be collapsed under a custom heading like "watch Blu-ray movie". This is something even the less tech savvy members of the household will get.
It would be nice if we didn't even have to worry about different standards. If you could just use whichever remote you liked and have it work everywhere, we'd be thrilled. But we don't live in this utopian paradise where technology makes perfect sense. An iPhone is a good backup for your remote control, but it isn't about to replace it. If it does, it's going to be a long way off. This is especially true when smartphone usage is hovering around 30%. A good old-fashioned universal remote will serve you better than a smartphone.
Image credit: Logitech, NewKinetix