While there are unofficial cracks (or hacks) for JK1, like just about every other PC game in existence, there is really no need for them (MotS is another story).
Why? Because the "CD check" can be bypassed by copying a single small file from the second disc to your hard drive. It's extremely easy to do, a child could figure it out! No need to download or hack anything.
The second disc is needed for the second half of the game for the reasons people gave. You can avoid having to insert the discs every time by use of the "do it yourself" cd check bypass. Most people just used this method for ease of use during multiplayer. For SP you don't want to miss the awesome cutscenes and music.
It's fun, because it's arcane knowledge now but back in the day everybody knew that! I feel old... but it's fun teaching the padawans old tricks.
PM me if you have further questions. And remember of coures that we don't condone piracy here even of old (and classic!) games. Glad you purchased yours legit!