You quoted the following, and I'd just like to put it in context a little...
Bikkus, you should all wander about for the benefit and happiness of the majority, help the people of this world, support and provide well-being to all dieties and human beings.
Vinaya Piṭaka. 1.23 "Caratha, bhikkhave, cārikaṃ bahujana-hitāya bahujana-sukhāya lokānukampāya, atthāyahitāyasukhāya devamanussānaṃ. Mā ekena dve agamittha."
This verse was spoken to sixty arahants
... in other words, sixty people who had already achieved the goal, had seen through the illusions of the world and fulfilled the holy life. This was said so that they could share the Dhamma which they had learned from the Buddha and pass it onto others so that they too could be liberated.
I trust you can see from this the difference between what the Buddha was exhorting to these sixty arahants versus that of the bodhisattva vow with which you are familiar.
In essence, the Buddha's intentions were to overcome suffering... first his own, and once he knew how to do it, use the remainder of his life to communicate the method to others so they could overcome their suffering too. The essential part is that one must focus on one's own enlightenment, achieve the goal and then they can be (and genuinely will be) of use to others.
This approach is expressed in such suttas as...
SN 47.19: Sedaka Sutta
http://www.accesstoinsight.org/tipitaka ... .than.html
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I have heard that on one occasion the Blessed One was living among the Sumbhas. Now there is a Sumbhan town named Sedaka. There the Blessed One addressed the monks, "Monks!"
"Yes, lord," the monks responded.
The Blessed One said, "Once upon a time, monks, a bamboo acrobat, having erected a bamboo pole, addressed his assistant, Frying Pan: 'Come, my dear Frying Pan. Climb up the bamboo pole and stand on my shoulders.'
"'As you say, Master,' Frying Pan answered the bamboo acrobat and, climbing the bamboo pole, stood on his shoulders.
"So then the bamboo acrobat said to his assistant, 'Now you watch after me, my dear Frying Pan, and I'll watch after you. Thus, protecting one another, watching after one another, we'll show off our skill, receive our reward, and come down safely from the bamboo pole.'
"When he had said this, Frying Pan said to him, 'But that won't do at all, Master. You watch after yourself, and I'll watch after myself, and thus with each of us protecting ourselves, watching after ourselves, we'll show off our skill, receive our reward, and come down safely from the bamboo pole.'
"What Frying Pan, the assistant, said to her Master was the right way in that case.
"Monks, a frame of reference is to be practiced with the thought, 'I'll watch after myself.' A frame of reference is to be practiced with the thought, 'I'll watch after others.' When watching after oneself, one watches after others. When watching after others, one watches after oneself.
"And how does one, when watching after oneself, watch after others? Through pursuing [the practice], through developing it, through devoting oneself to it. This is how one, when watching after oneself, watches after others.
"And how does one, when watching after others, watch after oneself? Through endurance, through harmlessness, and through a mind of kindness & sympathy. This is how one, when watching after others, watches after oneself.
"A frame of reference is to be practiced with the thought, 'I'll watch after myself.' A frame of reference is to be practiced with the thought, 'I'll watch after others.' When watching after oneself, one watches after others. When watching after others, one watches after oneself."