Dhamma could lead to the end of suffering, which is something most people would be interested in right?
No, that is not what most people are interested in. Most people are interested in worldly goals like making more money, having a beautiful girl/boyfriend, having a big house, glory, fame etc. It is only for those who have seen it all and have seen the inherent nature of suffering in all these things or for those very intelligent few who can through means of mere intellect know that all these things bring only suffering, only they came to the Dhamma.
Yes most people are interested in the idea of 'end of suffering' that's what all the politicians and priests promise but, they choose the temporary end via fulfilling sensual pleasures.
Is this because of indifference and thus ill-will and aversion? Is it because of delusion? Laziness and lethargy, or other parts of the five hindrances?
No, all these hindrances come after you start practicing the Dhamma. It is basically because of ignorance of the fact that there is another path of wisdom called the Dhamma and also by having wrong views about the Dhamma.
And why do people react so hostile when discussing achievements such as having better concentration, more equanimity etc.? Why don't they see it as an opportunity to learn something new?
Because all these achievements don't give you profit and success in worldly terms. Society wants you to be its slave and not a free individual. Think about it, if everyone attains equanimity then who is going to go on borders and wage war.
Why is there such a lack of enthusiasm and a drive to search for wisdom?
That's a matter of personal intelligence. Lack of enthusiasm for wisdom only denotes the naivety of an individual.