As an old school gamer I find most games easier nowadays, back in the 8bit era games were made harder, often to increase the play length or hide the fact that a game wasn't really complete. Of course back then all gamers were 'hardcore' because gaming was more of a niche market. Perhaps that is why I often equate 'hardcore' more to difficulty or depth, where as a lot of gamers seem to think that 'hardcore' just means M rated.
In general on the Wii though 'casual' games are usually easier and more accessible than 'hardcore' games are. Casual gamers are also thought to be incapable of using the full Wii controls, hence the Wiimote only options in many sports titles to give them both 'hardcore' and 'casual' appeal.
The reviewing gap between casual and hardcore is evident in something like Carnival Games. If I was to rate it I would score it around a 4 because it lacks any depth or real skill requirement (lot of hit or miss type games), yet I know people who would score it a 9 because they can just pick it up and play it without any real learning curve. Likewise I'd rate something like MP3 a 9 and they'd rate it a 4 because it was too much for them.