Salaries are private information. While there are arguments to be made for disclosing them (pay transparency is a big one), in Western workplace cultures it's up to the employee to disclose his salary if he so chooses1 and up to the employer to not spread the information around. Employees in those culture have the reasonable expectation that their employer will not publish their salary info without consent. The employer-employee is a business transaction like any other and the salary they negotiate is of no concern to a third party.
With that in mind, is it a good idea to announce raises publicly? No, it's not. The only perceived benefit I can see would be recognising high performers and incentivising others to similarly perform at a high level. This can be accomplished perfectly during regular performance evaluations or other one-on-one meetings between employee and manager. Meanwhile, the possible downsides or averse reactions vastly outweigh any benefit they might have, from upsetting people who didn't get a raise to animosity between coworkers when someone receives a higher raise.
Even worse, people generally have a very incomplete picture of how coworkers spend their time and how well they are really performing. Because of that, instead of having the intended effect, it's vastly more likely that disclosing raises would result in one of the following:
I worked so much overtime on my project while Jim just puts in his 9-to-5 and yet he got a much larger raise. Clearly performance isn't being rewarded here.
The only way to combat this would be to provide arguments for every raise and that is even more likely to cause problems. If you want to acknowledge or publicly recognize people for putting in amazing work, do so in a status meeting, a work event or a project debriefing. It's likely to have a much more positive effect.
To summarise: disclosing raises is a potential minefield for workplace morale with little to no benefit.
Note that companies that have made salary information public are an exception here. But even there it's better to acknowledge people directly and not tie it to raises as it's unlikely that people will link the two as you might want them to.
1 In fact, that right is usually protected.