A commitment to providing all human beings the golden opportunity to develop themselves is so vital, not only to the people here, but all around.
第一个问题是：为何用 to providing，不都是不定式么？
第二个问题是：but 和前面的 to...并列，那不应该是 but to all round 吗?
问题1、为何用 to providing，不都是不定式么？
这里用 to providing 或不定式 to provide 都可以。由于承诺做某事时，名词commitment后面既可接不定式 to do sth，也可接 to doing sth。如：
1. 接不定式 to do sth的例子
The hospital has a commitment to provide the best possible medical care. 这家医院承诺要提供最好的医疗服务。
The government is trying to back out of its commitment to reduce pollution. 政府曾承诺降低污染，目前想变卦了。
The government has manifestly failed to raise educational standards, despite its commitment to do so. 尽管政府承诺提升教学水平，但显然未能做到。
2. 接 to doing sth的例子
the government’s commitment to simplifying the way companies are taxed. 政府简化公司纳税手续的承诺
Do you think we can sustain our commitment to delivering the papers on time ? 你觉得大家还能按时递交文件吗？
The company’s commitment to providing quality at a reasonable price has been vital to its success. 这家公司保证供货质优价廉的承诺对它的成功起了决定性有哪些用途。
问题2、but 和前面的 to...并列，那不应该是 but to all round 吗?
是的，原则上说 not only…but …所连接的两个成分应是对称结构，但有时（特别是在口语或非正式文体中）也会连接非对称结构，关于这个问题，英语答疑网曾有过非常不错的解答，请参见：http://ask.yygrammar.com/q|2658.html。下面是有关内容的摘录：
▲在一般情况下，not only…but also…作为并列连词，应该用于连接两个平结构或相同的句子成分，如：
Not only the students but also their teacher is enjoying the film. 不只学生们在赏析这部影片，他们的老师也在赏析这部影片。（连接主语）
He not only read the book, but also remembered what he had read. 他不但看过这本书，而且记得书的内容。（连接谓语）
The claims were not only quite false but also very nearly dishonest. 这需要不止是相当无依据的，而且几乎是不诚实的。（连接表语）
If this project fails it will affect not only our department, but also the whole organization. 如果这个策略不成功，这不只不会干扰大家这个部门，而且会干扰整个组织。（连接宾语）
There are problems not only with the students, but also with the teachers themselves. 不但学生们有难点，教师们自己也有。（连接定语）
We go there not only in winter, but also in summer. 大家不只冬季去那儿，而且夏季也去。（连接状语）
▲以上说的是“一般情况”，但也有“非一般的状况”，即它所连接的两个成分并不是平结构或相同的句子成分，如：
Wood flooring not only cleans easily, but it’s environmentally friendly into the bargain. 木地板不光容易打扫，而且还环保。（摘自《柯林斯Cobuild高阶英汉双解学习词典》）
His headache and fatigue not only subsided, but, what is more, his craving for alcohol disappeared. 不但他的头疼和疲劳减累轻了，而且他嗜酒的问题也消失了。（摘自《柯林斯英语语法系列——限定词及数目词》）
从网上查了一下，这个句子源于全国大学生英语演讲比赛一等奖获得者顾秋陪的演讲稿，换句话说，这个句子源于一名大学生的口语表达，所以出现不对称的表达也非常正常。
附原句翻译：
A commitment to providing all human beings the golden opportunity to develop themselves is so vital, not only to the people here, but all around.
承诺为全人类提供好的机会来进步自我至关要紧，不只对在坐的人来讲是如此，对大家周围所有人来讲也是这样！
