To be fair most people will only ever need to use an IDC tool once to complete an installation and as long as you are installing just 1 wire in each IDC terminal and are careful to push the tool in upright it should be fine for several insertions. The trouble is many people have never used an IDC tool before so can easily damage the plastic tools by trying to push more than one wire in, having the tool back to front or not holding it straight when pushing it down. For these people ordering a second one is a good idea, it saves on postage or having to go running off and pay crazy prices from a DIY shop to complete the job if you damage the first one.
If you have two or three jobs to do, perhaps helping out a couple of family members with a similar installation it might be an idea to go for the tool with the metal blade as it will probably last longer than the all plastic type.
If you want a tool that you are going to use several times then better to get the proper tool that has a metal head complete with a little pair of snips that trims the wire when pressed into the IDC terminal as this type of tool will last for thousands of insertions and works much better when installing more than one wire into the terminal. They also make a satisfying click so you know when you have pushed the wire fully home.