Not all Windows Phones are created equal - otherwise they wouldn't be known by different phone models.
Some apps, for example, require a gyroscope to work - for sure that won't work in a Windows Phone that doesn't a gyroscope. Some apps require more RAM. For other apps, the publisher simply may have defined certain criteria which your phone doesn't meet.
Those "tricks" are security risks. So, apps can only be installed through the store (or if you've got a developer unlocked phone). Nonetheless, if an app is listed as "unsupported" for a certain phone, even a developer unlocked phone won't install it. No fuzzy workarounds. And Windows Phones and the world are safer.