Bloatware is a term given to applications installed in smart phones or tablets which cannot be easily removed. This seems to be a practice that phone manufacturers/service providers have been using since these devices were introduced. I suspect that these guys are paid to install this on your device, but what is the big deal?
First, you phone or tablet has a finite amount of memory and processor power. Many of these bloatware programs remain in memory and are also running in the background. This slows your phone down and takes memory away from you. You may want additional memory and processor power for applications of YOUR choosing: pictures, videos or anything that YOU deem important to save to you phone.
Additionally, these programs are sometimes written poorly opening your phone up to potential security risks, see Security flaws.
Removing bloatware, specifically on the Android operating systems is a pain. You must first root your phone and install an app to remove the bloatware. When you root your phone, you may "brick" the phone which renders it inoperative and voids your warranty.
Samsung may be listening. Less bloatware has been reported in Samsung S5 and S6. It seems to me that bloatware opens the bloatware author and installer up to lawsuits when security holes damage the user's phone or causes important data to end up in the wrong hands. Hopefully liability concerns will prompt manufacturers and carriers to think twice before installing this on their phones. As a customer, you too have the power in your wallet to include bloatware in your purchase decision.