I think the main problem of danger in Thailand is to do with farangs' lack of information about the violence in Bangkok/Thailand. The converse is true with Thais reading too much into what they see and hear in the news.
Many foreigners in their home country read the news and watch TV and hear about all of the violence and will say that their country is no longer safe. However, when they come to Thailand they are often unaware (ignorant ?) of the violence which happens in Thai society.Just have a look at where most farangs get their news.
1. Newspapers. Have a look at the Bangkok Post and The Nation. How often is it that you read about some assault on a foreigner or some grisly murder taking place? Not that often. Just have a look at Thai Rath website or the Thai news channels. You will often see stories about some rape or some extreme murder (and then the outcry about how violent Thai society is becoming. Obviously, the Pattaya Mail and the Phuket Gazette are slightly different, but because they are not dailies many people do not get that daily intake of violence, it makes
2. Internet – this is more of a recent phenomenon, but is one reason why farangs are becoming more aware of the violence that is taking place.
3. TV – Most farangs don't really watch Thai TV and cable won't report on much the violence that takes place in Bangkok and Thailand.
I would say that until very recently most farangs have been generally unaware of most of the violence that is taking place in Thailand. With things like the internet, this is changing. I don't think there is really been a very large increase in violence in Thailand, but I just think that farangs are becoming more aware of the violence in Thai society and particularly when it is directed against farangs in general.
If you really want to see if there has been an increase in the number of reported crimes, have a look at the Thai police criminal stats directly: http://www.police.go.th/dn_main.htm
There has certainly been an increase in the number of crimes directed towards humans (murder, manslaughter, rape etc) from 33,000 in 1999 to 45,000 in 2004.
However, if you look at rapes it is difficult to know what percentage is because of the actual increase in the number of rapes which have occurred or just an increase in the number of people that are reporting rapes. I think it is a mixture of both, but over the last 5-10 years the Police have tried to make the reporting of rapes somewhat more palatable (previously it was horrific, who the fuck wants to meet their attacker face-to-face when reenacting the crime!). Many sexual assaults are also 'settled' so they might not be on the books.
I remember a Thai teacher and some of her friends visiting New Zealand in 1999 and they thought it must be great living in New Zealand where there is no violence and everyone is safe – this was based on their observation that very few NZ houses had large fences in comparison with Thailand! One of them said it would be much safer in New Zealand for their children to go to school by themselves. I commented that that was not true and mentioned to them the story of a girl (Teresa McCormack?) who was kidnapped on her way to school in 1987. I wasn't actually living in NZ at the time, but come back to NZ for 7 weeks over Christmas and my grandmother's next door neighbour saying they wouldn't let their 8 year old grand daughter walk the 250 metres to the local primary school. I am sure you remember the fear and hysteria which gripped the nation over that case. I just had a different perception what they had. In hindsight though, what happened to one girl out of 300,000 students is hardly an indicator that all NZ children might be kidnapped and murdered.
Yep, ignorance is bliss!