Yep the eternal debate Yen Sid.
Part of the reason live casinos have them is the travel factor. Plenty of people drive for a good 30mins or even more to get to their local casino, and want an enjoyable night of poker when they get there. If their AA is busted after 5 mins and they are in a freezeout, well im sorry but they have come all that way for nothing!. At least with rebuys they can safely go into their pockets for another set of chips and know when they leave the house they are guaranteed an hr of live poker at least. They also make the game more fun. It can become like an all in frenzy during rebuys, and ofc you see some total shite turned over for preflop all ins

. This appeals to the gamblers amongst the poker players and if you are at a fun table it can really liven the game up and get people playing loose. PERSONALLY I like them because they make the game chip rich. In a 10 pound rebuy it is not uncommon for everyone at the table to have, on average, 5 rebuys each. This makes for a very deep stacked game after the rebuys are over. I play deep stacked cash games every day and this is the form of poker I like best. You get a lot of play in this case, and can see a lot of flops against the weaker players. This is miles closer to "true" poker for me than some shitty freezeout where you are down to 10 big blinds after 4 levels.
The major disadvantage I can see to rebuys, and I guess the reason the people who dislike them DO dislike them is the cost factor. Yes they increase the prize pool at the same rate as they cost the players, but the cost to you before you enter is unknown. The major attraction I think for most MTT players is the fact their loss is "set" before they start. That is in a 20 dollar MTT, although the first prize which you have a shot at may be many thousands of dollars, the worst you can come off is 20 dollars down, your original entry fee. In a rebuy its not clear cut, you may end up spending many many times over the cost of the entry fee (lol believe me I have been there) - for no return. If this worries you then you could of course set yourself a "rebuy limit" and a stop loss therfore. However this is criminally bad in my opinion. If you are a winning poker player, a rebuy in a rebuy tournament will always be +ev for you, so you should always take it.
Personally I like rebuys yen, for the reasons I stated above. They are a TON of fun and you get to play some real deep stacked poker in a tournament situation after. There are plenty of freezeouts around as well, infact far many more than rebuy tournaments - so if you dont like the rebuys you can always steer clear of them.
Jez